Download Measurement of Corpus Callosum in Sudanese Population Using MRI

‫بسم اهلل الرمحن الرحيم‬
Sudan university for Science & Technology
College of Graduate Studies
Measurement of Corpus Callosum in
Sudanese Population Using MRI
A thesis submitted in Partial fulfillment of the requirement of the degree of M.
Sc. In Diagnostic Radiologic Technology
Prepared by : Abdalselam Al Sanos Nasser Abdelhafidh
Supervised by :
Dr. Caroline Edward Ayad Khalill
2016
Chapter one
Introduction
1-1. INTRODUCTION
Corpus callosum (CC) is the main fiber tract connecting the cortical and
subcortical regions of the right and left hemispheres and plays an essential role
in the integration of information between the two hemispheres (Gupta ,et al
2008).Position and size of the corpus callosum is well appreciated in median
sections. The anterior end is called “the genu", the median region "the corpus"
and the posterior region "the splenium". Nerve fibres of the corpus callosum
radiate into the white area of each hemisphere dispersing to the various regions
of the cerebral cortex ( William , et al 1989).
Regarding differences in the size of organs in humans including (CC) according
to race/ethnicity in various parts of the world, (CC) dimensions, morphology
and sex-related differences have been of interest to researchers (mourgela , et al
2007) .By using magnetic resonance imaging (MRI), the dimensions of (CC)
including size, diameters, age morphology and also gender-related differences
have been determined in several studies ( Peterson, et al Permudez et al ,
2001).Most of the studies of (CC) measurements have been performed on
Caucasian samples (Sulivan , et al ; Witelson et al 2001, 1989)and there are
very few studies of (CC) in the Indian population(Banka et al 1996; Suganthy
et al , 2003) however and to the best of our knowledge, no study was conducted
in the open literature regarding Sudanese population for Corpus
callosum measurements. Moreover greater numbers of studies are carried out on
MRI scans.
Morphological deviations from normal may serve as an index for the presence
and progress of various neuropathological conditions The present study was
conducted using MRI scans to get inclusive data regarding (CC) in normal adult
Sudanese population and to present the results of callosal anatomy in
association to gender and age-related differences as well as to reveal the help of
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magnetic resonance imaging (MRI) in demonstrating the neuroanatomy of the
corpus callosum. This will give normative data on (CC) morphology in the
population under study and thus establish reference values for studying age,
gender and racial differences.
1.2 Statement of the problems:
Agenesis of the corpus callosum (ACC) is an anomaly that may occur in
isolation or in association with other central nervous system (CNS) or
systemic malformations. Because the corpus callosum may be partially or
completely absent. The term digenesis has also been used to describe the
spectrum of callosal anomalies.
The normal appearance of the corpus
callosum. Along with the appearance on magnetic resonance imaging (MRI)
is important, to our knowledge no measurement had been done for normal
corpus callosum for sudanese population.
1.3 Objective of the study:
1.3.1 General objectives.
Measurement of corpus callosum in Sudanese Population Using MRI.
1.3.2 Specific objectives :
- To measure the corpus callosum length, genu, splenium, CCI.
- To correlate the measurement with age and gender..
- To correlate the measurement with subjects age and gender.
- The measure the head diameter ( brain AP, sagtal , transfer )
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CHAPTER TWO
Literature Review
2-1 Anatomy of the brain
2-1-1 Overview
Nothing in the world can compare with the human brain. This mysterious threepound organ controls all necessary functions of the body, receives and interprets
information from the outside world, and embodies the essence of the mind and
soul. Intelligence, creativity, emotion, and memories are a few of the many
things governed by the brain.
The brain receives information through our five senses: sight, smell, touch,
taste, and hearing; often many at one time. It assembles the messages in a way
that has meaning for us, and can store that information in our memory. The
brain controls our thoughts, memory and speech, movement of the arms and
legs, and the function of many organs within our body. It also determines how
we respond to stressful situations (such as taking a test, losing a job, or suffering
an illness) by regulating our heart and breathing rate.
2-1-2 Nervous system
The nervous system is divided into central and peripheral systems. The central
nervous system (CNS) is composed of the brain and spinal cord. The peripheral
nervous system (PNS) is composed of spinal nerves that branch from the spinal
cord and cranial nerves that branch from the brain. The PNS includes the
autonomic nervous system, which controls vital functions such as breathing,
digestion, heart rate, and secretion of hormones.
2-1-3 Skull
The purpose of the bony skull is to protect the brain from injury. The skull is
formed from 8 bones that fuse together along suture lines. These bones include
the frontal, parietal (2), temporal (2), sphenoid, occipital and ethmoid (see the
Fig. below). The face is formed from 14 paired bones including the maxilla ,
zygoma, nasal, palatine, lacrimal, inferior nasal conchae, mandible, and vomer.
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Fig( 2-1) Eight bones form the skull and fourteen bones form the face.
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Inside the skull are three distinct areas: anterior fossa, middle fossa, and
posterior fossa (see the Fig. below). Doctors sometimes refer to a tumor’s
location by these terms, e.g., middle fossa meningioma.
Fig(2-2) :The inside of the skull is divided into three areas called the
anterior, middle, and posterior fossae.
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Similar to cables coming out the back of a computer, all the arteries, veins and
nerves exit the base of the skull through holes, called foramina. The big hole in
the middle (foramen magnum) is where the spinal cord exits.
2-1-4 Brain
The brain is composed of the cerebrum, cerebellum, and brainstem (see the Fig.
below).
Fig(2-3) : The brain is composed of three parts: the brainstem, cerebellum,
and cerebrum.
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The cerebrum is divided into four lobes: frontal, parietal, temporal, and
occipital.
The cerebrum is the largest part of the brain and is composed of right and left
hemispheres. It performs higher functions like interpreting touch, vision and
hearing, as well as speech, reasoning, emotions, learning, and fine control of
movement.
The cerebellum is located under the cerebrum. Its function is to coordinate
muscle movements, maintain posture, and balance.
The brainstem includes the midbrain, Pons, and medulla. It acts as a relay
center connecting the cerebrum and cerebellum to the spinal cord. It performs
many automatic functions such as breathing, heart rate, body temperature, wake
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and sleep cycles, digestion, sneezing, coughing, vomiting, and swallowing. Ten
of the twelve cranial nerves originate in the brainstem.
The surface of the cerebrum has a folded appearance called the cortex. The
cortex contains about 70% of the 100 billion nerve cells. The nerve cell bodies
color the cortex grey-brown giving it its name – gray matter (see the Fig.
below). Beneath the cortex are long connecting fibers between neurons, called
axons, which make up the white matter.
Fig(2-4) : The surface of the cerebrum is called the cortex. The cortex
contains neurons (grey matter), which are interconnected to other brain areas
by axons (white matter). The cortex has a folded appearance. A fold is called
a gyrus and the groove between is a sulcus.
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The folding of the cortex increases the brain’s surface area allowing more
neurons to fit inside the skull and enabling higher functions. Each fold is called
a gyrus, and each groove between folds is called a sulcus. There are names for
the folds and grooves that help define specific brain regions. (Williams Pl;
Warwiek ,1989)
2-1-5 Right brain – left brain
The right and left hemispheres of the brain are joined by a bundle of fibers
called the corpus callosum that delivers messages from one side to the other.
Each hemisphere controls the opposite side of the body. If a brain tumor is
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located on the right side of the brain, your left arm or leg may be weak or
paralyzed.
Not all functions of the hemispheres are shared. In general, the left hemisphere
controls speech, comprehension, arithmetic, and writing. The right hemisphere
controls creativity, spatial ability, artistic, and musical skills. The left
hemisphere is dominant in hand use and language in about 92% of people.
2-1-6 Lobes of the brain
The cerebral hemispheres have distinct fissures, which divide the brain into
lobes. Each hemisphere has 4 lobes: frontal, temporal, parietal, and occipital
(see the Fig below). Each lobe may be divided, once again, into areas that serve
very specific functions. It’s important to understand that each lobe of the brain
does not function alone. There are very complex relationships between the lobes
of the brain and between the right and left hemispheres.
2-1-6-1 Frontal lobe; the main functions are:
a- Personality, behavior, emotions.
b- Judgment, planning, problem solving.
c- Speech: speaking and writing (Broca’s area).
d- Body movement (motor strip).
e- Intelligence, concentration, self awareness.
2-1-6-2 Parietal lobe
a-
Interprets language, words
b-
Sense of touch, pain, temperature (sensory strip)
c-
Interprets signals from vision, hearing, motor, sensory and memory
d-
Spatial and visual perception
2-1-6-3 Occipital lobe

Interprets vision (color, light, movement)
2-1-6-4 Temporal lobe
a- Understanding language (Wernicke’s area).
b- Memory.
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c- Hearing.
d- Sequencing and organization.
Messages within the brain are carried along pathways. Messages can travel from
one gyrus to another, from one lobe to another, from one side of the brain to the
other, and to structures found deep in the brain (e.g. thalamus, hypothalamus).
2-1-7 Deep structures:
2-1-7-1 Hypothalamus - is located in the floor of the third ventricle and is the
master control of the autonomic system. It plays a role in controlling behaviors
such as hunger, thirst, sleep, and sexual response. It also regulates body
temperature, blood pressure, emotions, and secretion of hormones.
2-1-7-2 Pituitary gland - lies in a small pocket of bone at the skull base called
the sella turcica. The pituitary gland is connected to the hypothalamus of the
brain by the pituitary stalk. Known as the “master gland,” it controls other
endocrine glands in the body. It secretes hormones that control sexual
development, promote bone and muscle growth, respond to stress, and fight
disease.
2-1-7-3 Pineal gland - is located behind the third ventricle. It helps regulate the
body’s internal clock and circadian rhythms by secreting melatonin. It has some
role in sexual development.
2-1-7-4 Thalamus - serves as a relay station for almost all information that
comes and goes to the cortex (see the Fig. below). It plays a role in pain
sensation, attention, alertness and memory.
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Fig(2-5) Coronal cross-section showing the basal ganglia.
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2-1-7-5 Basal ganglia - includes the caudate, putamen and globus pallidus.
These nuclei work with the cerebellum to coordinate fine motions, such as
fingertip movements.
2-1-7-6 Limbic system - is the center of our emotions, learning, and memory.
Included in this system are the cingulate gyri, hypothalamus, amygdala
(emotional reactions) and hippocampus (memory).
2-1-7-7 Cranial nerves
The brain communicates with the body through the spinal cord and twelve pairs
of cranial nerves (see the Fig. below). Ten of the twelve pairs of cranial nerves
that control hearing, eye movement, facial sensations, taste, swallowing and
movement of the face, neck, shoulder and tongue muscles originate in the
brainstem. The cranial nerves for smell and vision originate in the cerebrum.
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Fig(2-6) : The Roman numeral, name, and main function of the twelve
cranial nerves.
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Table (2.1) : The Roman numeral, name, and main function of the twelve
cranial nerves
Number
Name
Function
I
olfactory
Smell
II
Optic
Sight
III
oculomotor
moves eye, pupil
IV
trochlear
moves eye
V
trigeminal
face sensation
VI
abducens
moves eye
VII
Facial
moves face, salivate
VIII
vestibulocochlear
hearing, balance
IX
glossopharyngeal
taste, swallow
X
Vagus
heart rate, digestion
XI
accessory
moves head
XII
hypoglossal
moves tongue
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2-1-8 Meninges
The brain and spinal cord are covered and protected by three layers of tissue
called meninges. From the outermost layer inward they are: the dura mater,
arachnoid mater, and pia mater.
The dura mater is a strong, thick membrane that closely lines the inside of the
skull; its two layers, the periosteal and meningeal dura, are fused and separate
only to form venous sinuses. The dura creates little folds or compartments.
There are two special dural folds, the falx and the tentorium. The falx separates
the right and left hemispheres of the brain and the tentorium separates the
cerebrum from the cerebellum.
The arachnoid mater is a thin, web-like membrane that covers the entire brain.
The arachnoid is made of elastic tissue. The space between the dura and
arachnoid membranes is called the subdural space.
The pia mater hugs the surface of the brain following its folds and grooves. The
pia mater has many blood vessels that reach deep into the brain. The space
between the arachnoid and pia is called the subarachnoid space. It is here where
the cerebrospinal fluid bathes and cushions the brain.
2-1-9 Ventricles and cerebrospinal fluid
The brain has hollow fluid-filled cavities called ventricles (see the Fig. below).
Inside the ventricles is a ribbon-like structure called the choroid plexus that
makes clear colorless cerebrospinal fluid (CSF). CSF flows within and around
the brain and spinal cord to help cushion it from injury. This circulating fluid is
constantly being absorbed and replenished.
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Fig (2-7) : CSF is produced inside the ventricles deep within the brain. CSF
fluid circulates inside the brain and spinal cord and then outside to the
subarachnoid space. Common sites of obstruction: 1) foramen of Monro, 2)
aqueduct of Sylvius, and 3) obex.
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There are two ventricles deep within the cerebral hemispheres called the lateral
ventricles. They both connect with the third ventricle through a separate
opening called the foramen of Monro. The third ventricle connects with the
fourth ventricle through a long narrow tube called the aqueduct of Sylvius.
From the fourth ventricle, CSF flows into the subarachnoid space where it
bathes and cushions the brain. CSF is recycled (or absorbed) by special
structures in the superior sagittal sinus called arachnoid villi.
A balance is maintained between the amount of CSF that is absorbed and the
amount that is produced. A disruption or blockage in the system can cause a
buildup of CSF, which can cause enlargement of the ventricles (hydrocephalus)
or cause a collection of fluid in the spinal cord (syringomyelia).
2-1-10 Blood supply
Blood is carried to the brain by two paired arteries, the internal carotid arteries
and the vertebral arteries (see the Fig. below). The internal carotid arteries
supply most of the cerebrum.
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Fig(2-8):The common carotid artery courses up the neck and divides into
the internal and external carotid arteries. The brain’s anterior circulation
is fed by the internal carotid arteries (ICA) and the posterior circulation is
fed by the vertebral arteries (VA). The two systems connect at the Circle of
Willis.
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The vertebral arteries supply the cerebellum, brainstem, and the underside of the
cerebrum. After passing through the skull, the right and left vertebral arteries
join together to form the basilar artery. The basilar artery and the internal
carotid arteries “communicate” with each other at the base of the brain called
the Circle of Willis (see the Fig. below). The communication between the
internal carotid and vertebral-basilar systems is an important safety feature of
the brain. If one of the major vessels becomes blocked, it is possible for
collateral blood flow to come across the Circle of Willis and prevent brain
damage.
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Fig(2-9): Top view of the Circle of Willis. The internal carotid and
vertebral-basilar systems are joined by the anterior communicating and
posterior communicating arteries.
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The venous circulation of the brain is very different than the rest of the body.
Usually arteries and veins run together as they supply and drain specific areas of
the body. So one would think there would be a pair of vertebral veins and
internal carotid veins. However, this is not the case in the brain. The major vein
collectors are integrated into the dura to form venous sinuses (see the Fig.
below) - not to be confused with the air sinuses in the face and nasal region. The
venous sinuses collect the blood from the brain and pass it to the internal jugular
veins. The superior and inferior sagittal sinuses drain the cerebrum, the
cavernous sinuses drains the anterior skull base. All sinuses eventually drain to
the sigmoid sinuses, which exit the skull and form the jugular veins. These two
jugular veins are essentially the only drainage of the brain.
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Fig(2-10) : Three quarter view of the dural covering of the brain depicts
the two major dural folds, the falx and tentorium along with the venous
sinuses.
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2-1-11 Language
In general, the left hemisphere of the brain is responsible for language and
speech and is called the "dominant" hemisphere. The right hemisphere plays a
large part in interpreting visual information and spatial processing. In about one
third of individuals who are left-handed, speech function may be located on the
right side of the brain. Left-handed individuals may need special testing to
determine if their speech center is on the left or right side prior to any surgery in
that area.
Aphasia is a disturbance of language affecting production, comprehension,
reading or writing, due to brain injury – most commonly from stroke or trauma.
The type of aphasia depends on the brain area affected.
Broca’s area lies in the left frontal lobe (Fig 3). If this area is damaged, one
may have difficulty moving the tongue or facial muscles to produce the sounds
of speech. The individual can still read and understand spoken language but has
difficulty in speaking and writing (i.e. forming letters and words, doesn't write
within lines) – called Broca's aphasia.
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Wernicke's area lies in the left temporal lobe (Fig 3). Damage to this area
causes Wernicke's aphasia. The individual may speak in long sentences that
have no meaning, add unnecessary words, and even create new words. They can
make speech sounds, however they have difficulty understanding speech and
are therefore unaware of their mistakes.
2-1-12 Memory
Memory is a complex process that includes three phases: encoding (deciding
what information is important), storing, and recalling. Different areas of the
brain are involved in memory depending on the type of memory.
Short-term memory, also called working memory, occurs in the prefrontal
cortex. It stores information for about one minute and its capacity is limited to
about 7 items. For example, it enables you to dial a phone number someone just
told you. It also intervenes during reading, to memorize the sentence you have
just read, so that the next one makes sense.
Long-term memory is processed in the hippocampus of the temporal lobe and
is activated when you want to memorize something for a longer time. This
memory has unlimited content and duration capacity. It contains personal
memories as well as facts and figures.
Skill memory is processed in the cerebellum, which relays information to the
basal ganglia. It stores automatic learned memories like tying a shoe, playing an
instrument, or riding a bike.
2-1-13 Cells of the brain
The brain is made up of two types of cells: nerve cells (neurons) and glia cells.
2-1-13-1 Nerve cells
There are many sizes and shapes of neurons, but all consist of a cell body,
dendrites and an axon. The neuron conveys information through electrical and
chemical signals. Try to picture electrical wiring in your home. An electrical
circuit is made up of numerous wires connected in such a way that when a light
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switch is turned on, a light bulb will beam. A neuron that is excited will
transmit its energy to neurons within its vicinity.
Neurons transmit their energy, or “talk”, to each other across a tiny gap called a
synapse (see the Fig. below). A neuron has many arms called dendrites, which
act like antennae picking up messages from other nerve cells. These messages
are passed to the cell body, which determines if the message should be passed
along. Important messages are passed to the end of the axon where sacs
containing neurotransmitters open into the synapse. The neurotransmitter
molecules cross the synapse and fit into special receptors on the receiving nerve
cell, which stimulates that cell to pass on the message.
Fig(2-11): Nerve cells consist of a cell body, dendrites and axon. Neurons
communicate with each other by exchanging neurotransmitters across a
tiny gap called a synapse.
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2-1-13-2 Glia cells
Glias (Greek word meaning glue) are the cells of the brain that provide neurons
with nourishment, protection, and structural support. There is about 10 to 50
times more glia than nerve cells and is the most common type of cells involved
in brain tumors.
Astroglia or astrocytes transport nutrients to neurons, hold neurons in place,
digest parts of dead neurons, and regulate the blood brain barrier.
Oligodendroglia cells provide insulation (myelin) to neurons.
Ependymal cells line the ventricles and secrete cerebrospinal fluid (CSF).
Microglia digests dead neurons and pathogens.
Image. Huffington post/2007-12-17 lolbrain.jpg
A
Study droid.com/imagecords/oh/gm/cord-12372959-front.jpg
B
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C
Fig(2-12) :The corpus callosum:
http://brainmadesimple.com/uploads/7/8/8/5/7885523/_9017293.jpg
Fig (2-13) : Corpus callosum with Anatomography
https://en.wikipedia.org/wiki/corpus-collosum#/media /file:corpuscollosum.png
2-2 Anatomy of Corpus callosum
The corpus callosum ( Latin for "tough body"), also known as the callosal
commissure, is a wide, flat bundle of neural fibers beneath the cortex in the
eutherian brain at the longitudinal fissure. It connects the left and right cerebral
hemispheres and facilitates interhemispheric communication. It is the largest
white matter structure in the brain, consisting of 200–250 million contralateral
axonal projections.
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Corpus callosum is a bundle of nerve fibers in the longitudinal fissure of the
brain that enables corresponding regions of the left and right cerebral
hemispheres to communicate. The axons and dendrites of the neurons in the
corpus callosum synapse with cortical neurons on symmetrically related points
of the hemispheres. Thus, electrical stimulation of a point on one hemisphere
usually gives rise to a response on a symmetrically related point on the other,
by virtue of these callosal connections. The neurons in the corpus callosum
also are insulated by a myelin sheath, which facilitates the rapid conduction of
electrical impulses between the hemispheres. ( Gouliamos A,2007)
Diseases affecting the corpus callosum include Marchiafava-Bignami disease,
which is characterized by progressive demyelination of the neurons of the
corpus callosum. In addition, agenesis (imperfect development) of the corpus
callosum can cause intellectual disability and seizures. A reduced amount of
tissue in the corpus callosum also has been associated with attentiondeficit/hyperactivity disorder. (Warwiek, R. ,1989)
The corpus callosum has played an important role in the elucidation of
functions specific to each of the cerebral hemispheres. For example, studies of
individuals being treated for epilepsy in which the corpus callosum has been
severed, allowing the two hemispheres to function largely independently, have
revealed that the right hemisphere has more language competence than was
thought.
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Fig(2-14): Corpus callosum from above. (Anterior portion is at the top of
the image.)
https://en.wikipedia.org/wiki/corpus-collosum#/media /file:Gray733.png
Fig(2-15): Median sagittal section of brain (person faces to the left).
Corpus callosum visible at center, in light gray
https://en.wikipedia.org/wiki/corpus-collosum#/media /file:Gray720.png
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2-2-1 Structure
The posterior (back) portion of the corpus callosum is called the splenium; the
anterior (front) is called the genu (or "knee"); between the two is the truncus, or
"body", of the corpus callosum. The part between the body and the splenium is
often markedly narrowed and thus referred to as the "isthmus". The rostrum is
the part of the corpus callosum that projects posteriorly and inferiorly from the
anteriormost genu, as can be seen on the sagittal image of the brain displayed on
the right. The rostrum is so named for its resemblance to a bird's beak.
Corpus callosum
https://en.wikipedia.org/wiki/corpus-collosum#/media /file:Choroidplexus.jpg
On either side of the corpus callosum, the fibers radiate in the white matter and
pass to the various parts of the cerebral cortex; those curving forward from the
genu into the frontal lobe constitute the forceps anterior, and those curving
backward into the occipital lobe, the forceps posterior. Between these two parts
is the main body of the fibers which constitute the tapetum and extend laterally
on either side into the temporal lobe, and cover in the central part of the lateral
ventricle.
Thinner axons in the genu connect the prefrontal cortex between the two halves
of the brain; these fibers arise from a fork-like bundle of fibers from the
tapetum, the forceps anterior. Thicker axons in the mid body, or trunk of the
corpus callosum, interconnect areas of the motor cortex, with proportionately
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more of the corpus callosum dedicated to supplementary motor regions
including Broca's area. The posterior body of the corpus, known as the
splenium, communicates somatosensory information between the two halves of
the parietal lobe and the visual cortex at the occipital lobe, these are the fibers of
the forceps posterior.
2-2-2 Variation
Agenesis of the corpus callosum (ACC) is a rare congenital disorder that is one
of the most common brain malformations observed in human beings, in which
the corpus callosum is partially or completely absent. ACC is usually diagnosed
within the first two years of life, and may manifest as a severe syndrome in
infancy or childhood, as a milder condition in young adults, or as an
asymptomatic incidental finding. Initial symptoms of ACC usually include
seizures, which may be followed by feeding problems and delays in holding the
head erect, sitting, standing, and walking. Other possible symptoms may include
impairments in mental and physical development, hand-eye coordination, and
visual and auditory memory. Hydrocephaly may also occur. In mild cases,
symptoms such as seizures, repetitive speech, or headaches may not appear for
years.
ACC is usually not fatal. Treatment usually involves management of symptoms,
such as hydrocephaly and seizures, if they occur. Although many children with
the disorder lead normal lives and have average intelligence, careful
neuropsychological testing reveals subtle differences in higher cortical function
compared to individuals of the same age and education without ACC. Children
with ACC accompanied by developmental delay and/or seizure disorders should
be screened for metabolic disorders.
In addition to agenesis of the corpus callosum, similar conditions are
hypogenesis (partial formation), dysgenesis (malformed), and hypoplasia
(underdevelopment, including too thin). Recent studies have also linked
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possible correlations between corpus callosum malformation and autism
spectrum disorders.
2-2-3 Sexual dimorphism
The corpus callosum and its relation to sex has been a subject of debate in the
scientific and lay communities for over a century. Initial research in the early
20th century claimed the corpus to be different in size between men and
women. That research was in turn questioned, and ultimately gave way to more
advanced imaging techniques that appeared to refute earlier correlations.
However, advanced analytical techniques of computational neuroanatomy
developed in the 1990s showed that sex differences were clear but confined to
certain parts of the corpus callosum, and that they correlated with cognitive
performance in certain tests. One recent study using magnetic resonance
imaging (MRI) found that the midsagittal corpus callosum cross-sectional area
is, on average, proportionately larger in females.
2-2-4 Physiologic imaging
The ability to evaluate the form and function of the human mind has undergone
almost exponential growth and a paradigm shift in recent years. Functional
magnetic resonance imaging, for example, is now being used to analyze
physiology, in addition to the traditional use of MRI for studying anatomy.
Using diffusion tensor sequences on MRI machines, the rate at which molecules
diffuse in and out of a specific area of tissue, anisotropy (directionality), and
rates of metabolism can be measured. These sequences have found consistent
sex differences in human corpus callosal morphology and microstructure.
Morphometric analysis has also been used to study specific three-dimensional
mathematical relationships with MRIs, and have found consistent and
statistically significant differences across genders. Specific algorithms have
found significant gender differences in over 70% of cases in one review.
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2-2-5 Gender identity disorder
Research has been done on the shape of the corpus callosum in those with
gender identity disorder. Researchers were able to demonstrate that the shape
dimorphism of the corpus callosum at birth in people assigned male at birth who
self-identified as female was actually reversed, and that the same held true for
people assigned female at birth that self-identified as male, however, the shape
of the corpus callosum correlates better with the 'mental sex' of individuals
rather than their 'physical sex'. The relationship between the corpus callosum
and gender remains an active subject of debate in the scientific community.
The front portion of the corpus callosum has been reported to be significantly
larger in musicians than nonmusicians, and to be 0.75 cm2 or 11% larger in lefthanded and ambidextrous people than right-handed people. This difference is
evident in the anterior and posterior regions of the corpus callosum, but not in
the splenium. Other magnetic resonance morphometric study showed corpus
callosum size correlates positively with verbal memory capacity and semantic
coding test performance. Children with dyslexia tend to have smaller and lessdeveloped corpus callosum than their nondyslexic counterparts.
Musical training has shown to increase plasticity of the corpus callosum during
a sensitive period of time in development. The implications are an increased
coordination of hands, differences in white matter structure, and amplification
of plasticity in motor and auditory scaffolding which would serve to aid in
future musical training. The study found children who had begun musical
training before the age of six (minimum 15 months of training) had an increased
volume of their corpus callosum and adults who had begun musical training
before the age of 11 also had increased bimanual coordination.( Levitin, Daniel
J. 2005)
Clinical significance: Epilepsy: Electroencephalography is used to find the
source of electrical activity causing a seizure as part of the surgical evaluation
for a corpus callosotomy. The symptoms of refractory epilepsy can be reduced
25
by cutting the corpus callosum in an operation known as a corpus callosotomy.
(James E. 2007).
This is usually reserved for cases in which complex or grand mal seizures are
produced by an epileptogenic focus on one side of the brain, causing an
interhemispheric electrical storm. The work up for this procedure involves an
electroencephalogram, MRI, PET scan, and evaluation by a specialized
neurologist, neurosurgeon, psychiatrist, and neuroradiologist before surgery can
be considered.(Web MD. July 18, 2010)
2-2-6 Other disease: Anterior corpus callosum lesions may result in akinetic
mutism or tactile anomia. Posterior corpus callosum (splenium) lesions may
result in alexia (inability to read) without agraphia.
The cerebral cortex is divided into two hemispheres, connected by the corpus
callosum. A procedure to help patients alleviate the severity of seizures is called
split-brain procedure. As a result, a seizure that starts in one hemisphere is
isolated in that hemisphere, since a connection to the other side no longer exists.
However, this procedure is dangerous and risky.
2-2-7 History
The first study of the corpus with relation to gender was by R. B. Bean, a
Philadelphia anatomist, who suggested in 1906 that "exceptional size of the
corpus callosum may mean exceptional intellectual activity" and that there were
measurable differences between men and women. Perhaps reflecting the
political climate of the times, he went on to claim differences in the size of the
callosum across different races. His research was ultimately refuted by Franklin
Mall, the director of his own laboratory.(Bishop, Katherine M.; Wahlsten,
Douglas (1997). . Of more mainstream impact was a 1982 Science article by
Holloway and Utamsing that suggested sex difference in human brain
morphology, which related to differences in cognitive ability.( DelacosteUtamsing, C; Holloway, R. 1982).
26
More recent publications in the psychology literature have raised doubt as to
whether the anatomic size of the corpus is actually different. A meta-analysis of
49 studies since 1980 found that, contrary to de Lacoste-Utamsing and
Holloway, no sex difference could be found in the size of the corpus callosum,
whether or not account was taken of larger male brain size. [23] A study in 2006
using thin slice MRI showed no difference in thickness of the corpus when
accounting for the size of the subject.
(Luders, Eileen; Narr, Katherine
L.; Zaidel, Eran; Thompson, Paul M.; Toga, Arthur W., 2006)
2-2-8 Animals other than man:
The corpus callosum is found only in placental mammals (the eutherians), while
it is absent in monotremes and marsupials, as well as other vertebrates such as
birds, reptiles, amphibians and fish. (Other groups do have other brain structures
that allow for communication between the two hemispheres, such as the anterior
commissure, which serves as the primary mode of interhemispheric
communication in marsupials, and which carries all the commissural fibers
arising from the neocortex (also known as the neopallium), whereas in placental
mammals, the anterior commissure carries only some of these fibers. In
primates, the speed of nerve transmission depends on its degree of myelination,
or lipid coating. This is reflected by the diameter of the nerve axon. In most
primates, axonal diameter increases in proportion to brain size to compensate
for the increased distance to travel for neural impulse transmission. This allows
the brain to coordinate sensory and motor impulses. However, the scaling of
overall brain size and increased myelination have not occurred between
chimpanzees and humans. This has resulted in the human corpus callosum's
requiring double the time for interhemispheric communication as a macaque's.
(Gupta, 2008)
27
Fig(2-16): Sagittal post mortem section through the midline brain. The corpus
callosum is the curved band of lighter tissue at the center of the brain above
the hypothalamus. Its lighter texture is due to higher myelin content, resulting
in faster neuronal impulse transmission.
www.eucalyptusike.com/sitebuilder/images/corpus-col.jpg
The fibrous bundle as which the corpus callosum appears, can and does increase
to such an extent in humans that it encroaches upon and wedges apart the
hippocampal structures.(Kosar Ml, 2012)
28
Corpus callosum
https://en.wikipedia.org/wiki/corpus-collosum#/media /file:Gray733.png
A
https://en.wikipedia.org/wiki/corpus-collosum#/media /file:alisw100.jpg
B
https://en.wikipedia.org/wiki/corpus-collosum#/media /file:26638.mediumemphasizezing.corpus-callosum.png
C
Corpus callosum parts on MRI
Fig(2-17): Coronal T2 (grey scale inverted) MRI of the brain at the level
of the caudate nuclei emphasizing corpus callosum
29
https://en.wikipedia.org/wiki/corpus-collosum#/media /file: corpuscallosum.png
Fig(2-18) Ventricles of brain and basal ganglia. Superior view.
Horizontal section. Deep dissection
http://upload.wikipedia.org/wikipedia/commons/8/81/slide2GRe.jpg
Fig(2-19) : Ventricles of brain and basal ganglia. Superior view.
Horizontal section. Deep dissection
http://upload.wikipedia.org/wikipedia/commons/8/82/slide3GRe.jpg
31
2-3 physiology
2-3-1 Physiology of the Forebrain (Proencephalon)
2-3-1-1 Introduction
The forebrain (Proencephalon) is the largest part of the brain, most of which is
cerebrum. Other important structures found in the forebrain include the
thalamus, the hypothalamus and the limbic system. The cerebrum is divided
into two cerebral hemispheres connected by a mass of white matter known as
the corpus callosum. Each hemisphere is split into four lobes; the frontal,
parietal, occipital and temporal lobes. The surface of each hemisphere is made
up of grey matter known as the cerebral cortex and is folded to increase the
surface area available within the skull. The cortex has roles within perception,
memory and all higher thought processes. Inside the cortex is the white matter,
within which are a number of nuclei (grey matter), known as the basal nuclei.
The basal nuclei receive information from the cortex to regulate skeletal
movement and other higher motor functions. The thalamus functions to relay
sensory information to the cerebral cortex and the hypothalamus, regulating
visceral functions including temperature, reproductive functions, eating,
sleeping and the display of emotion. The limbic system describes a collection of
structures within the forebrain, including the amygdala and hippocampus, also
known as the 'emotional brain'. It is important in the formation of memories and
in making decisions and learning.
Table (2-2) Forebrain Structure and Function
Brain Region
Diencephalon
Diencephalon
Diencephalon
Telencephalon
Telencephalon
Telencephalon
Structure
Function
Thalamus
Organising sensory information
Hypothalamus Endocrine System, Thermoregulation
Pituitary
Endocrine System
Cerebral Cortex
Conciousness, language etc
Limbic System
Memory, motivation, emotion
Olfactory Bulb
Smell
31
2-3-1-3 Thalamus
The thalamus has many functions including processing and relaying sensory
information selectively to various parts of the cerebral cortex, translating signals
to the cerebral cortex from lower centres including auditory, somatic, visceral,
gustatory and visual systems and also regulating states of sleep and
wakefulness. The thalamus plays a major role in regulating arousal, levels of
consciousness and levels of activity.
2-3-1-4 Hypothalamus
The function of the hypothalamus is mainly related to the overall regulation of
the Endocrine System. The hypothalamus is closely related to the pituitary
gland, controlling a large proportion of the activity going to it. For a more
detailed analysis of the function of this part of the brain, please use the link:
Hypothalamus Anatomy and Physiology.
2-3-1-5 Pituitary
The function of the pituitary is mainly related to the production of hormones as
part of the Endocrine System. For further information on the pituitary gland
please use this link: Pituitary Gland Anatomy and Physiology.
2-3-1-6 Cerebral Cortex
The cerebral cortex is essential for memory, attention, awareness, thought,
language and consciousness. The outer layers of the cerebrum are made up of
grey matter. Grey matter is formed by neurons and their unmyelinated fibres.
The white matter below the grey matter of the cortex is formed predominantly
by myelinated axons (myelin is white in appearance). The surface of the
cerebral cortex is folded in mammals; more than two thirds of the surface is
within the grooves or "sulci". The cerebral cortex is connected to structures such
as the thalamus and the basal ganglia, sending information to them along
efferent connections and receiving information from them via afferent
connections. Most sensory information is routed to the cerebral cortex via the
32
thalamus. The cortex is commonly described as comprising three parts; sensory,
motor and association areas.
2-3-1-7 Sensory Areas
The sensory areas are the areas that receive and process information from the
senses. Inputs from the thalamus are called primary sensory areas. Vision,
hearing, and touch are processed by the primary visual cortex, primary auditory
cortex and primary somatosensory cortex. The two hemispheres of the cerebral
cortex receive information from the opposite (contralateral) side of the body.
Areas with lots of sensory innervation, such as the fingertips and the lips,
require more cortical area to process finer sensation. The association areas of
the brain function to produce a perception of the world enabling an animal to
interact with their environment effectively. There are a number of anatomical
areas of the brain responsible for organising this sensory information. The
parietal lobe is located within the dorsocaudal aspect of the cortex. The
temporal lobes are located laterally and the occipital lobes are located in the
caudal most aspect of the cortex. The frontal lobe or prefrontal association
complex is involved in planning actions and movement.
2-3-1-8 Motor Cortex
The motor cortex areas of the brain are located in both hemispheres of the
cortex and are shaped like a pair of headphones stretching from ear to ear. The
motor areas are related to controlling voluntary movements, especially fine
movements. There are two main types of connection between the motor cortex
and motor neurones found in the ventral horn of the spinal cord; the Pyramidal
tracts and the Extrapyramidal tracts.
Pyramidal tract connections are direct with no synapses in the brain stem.
Axons pass through the ventral aspect of the medulla oblongata. The
extrapyramidal tracts pass through the medulla oblongata outside the ventral
pyramidal tracts and have synapses within the brain stem nuclei. These synapses
33
make it possible for signals travelling down the extrapyramidal horns to be
influenced by other areas of the brain including the cerebrum.
The pyramidal tracts are responsible for aspects of fine motor skills that require
a degree of conscious thought and concentration. The extrapyramidal tracts are
generally responsible for activation of larger muscle groups and often work in a
coordinated manner to achieve smooth synchronous movements.
2-3-1-9 Limbic System
The Limbic system is made up of parts of the brain bordering the corpus
collosum. The Limbic system contains areas of cerebral cortex, the cingulate
gyrus (dorsally), the parahippocampus gyrus (ventrally), the amygdala, parts of
the hypothalamus (mamillary body) and the hippocampus. The Limbic system
is principally responsible for emotions and the various types of emotion can
affect the activity of the Autonomic Nervous System, facilitated by the
hypothalamus. For example, anger can lead to increased heart rate and blood
pressure.
2-3-1-10 Olfactory Bulb
The olfactory bulb is responsible for olfaction and the bulb itself is located
within the rostral forebrain area, supported by the cribiform plate and the
ethmoid bone. The olfactory nerves are connected directly to the limbic system
which is unique among mammalian sensory organs. As a result, olfaction plays
a central role and is particularly important in regulating/stimulating sexual
behavior in many species. Ventral Brain with Olfactory bulbs rostral (Human),(
Grays Anatomy, 1918)
34
2-3-2 Physiology of the corpus callosum
Fig( 2-20) : Physiology of the corpus callosum
o.tqn.com/d/biology/1/G/q/z/corpus-collosum.jpg
The corpus callosum (CC) links the cerebral cortex of the left and right
cerebral hemispheres and is the largest fibre pathway in the brain.
Gross anatomy
The corpus callosum is ~10cm in length and is C-shaped, like most of the
supratentorial structures, in a gentle upwardly convex arch.
It is divided into four parts (anterior to posterior):

rostrum (continuous with the lamina terminalis)

genu

trunk/body

splenium
Relations
Immediately above the body of the CC, lies the interhemispheric fissure in
which runs the falx cerebri, the anterior cerebral vessels. The superior surface of
35
the CC is covered by a thick layer of grey matter known as the indusium
griseum. On either side, the body is separated from cingulate gyrus by the
callosal sulcus. Attached to the concave undersurface of the CC is the septum
pellucidum anteriorly, and the fornix and its commissure posteriorly.
Although the CC can be seen as a single large fibre bundle connecting the two
hemispheres, a number of individual fibre tracts can be identified. These
include:
Genu: forceps minor : connect medial and lateral surfaces of the frontal lobes.
Rostrum: connecting the orbital surfaces of the frontal lobes Trunk (body):
pass through the corona radiata to the surfaces of the hemispheres. Trunk and
splenium: tapetum; extends along the lateral surface of the occipital and
temporal horns of the lateral ventricle. Splenium: forceps major; connect the
occipital lobes.
These connections can also be divided into: Homotopic connections those that
link similar regions on each side e.g. visual fields of motor/sensory areas of the
trunk. Heterotopic connections: those that link dysimilar areas
Blood supply
The corpus callosum (CC) has a rich blood supply, relatively constant and is
uncommonly involved by infarcts. The majority of the CC is supplied by the
pericallosal arteries (the small branches and accompanying veins forming the
pericallosal moustache) and the posterior pericallosal arteries, branches from the
anterior and posterior cerebral respectively. In 80% of patients additional supply
comes from the anterior communicating artery, via either subcallosal artery or
median callosal artery. (Henry Gray, et al , 1995)

subcallosal artery (50% of patients) is essentially a large version of a
hypothalmic branch, which in addition to supplying part of the
hypothalamus also supplies the medial portions of the rostrum and genu

median callosal artery (30% of patients) can be thought of as a more
extended version of the subcallosal artery, in that it travels along the same
36
course, supplies the same structures but additionally reaches the body of
the corpus callosum

posterior pericallosal artery (also known as splenial artery) supplies a
variable portion of the splenium. Its origin is inconstant, arising from P3
or branches thereof.
After periods of disinterest, neurosurgeons' attention to the corpus callosum has
been reawakened for a variety of reasons. For centuries, the large size, central
location, and widespread connections of the corpus callosum stimulated
investigations, which were motivated as much by scientific curiosity as by
therapeutic considerations. Callosal physiology has more recently been
important to surgeons concerned primarily with other structures, including those
neighboring the third ventricle, which can be approached through the corpus
callosum. But the principal motivation has been the role of the corpus callosum
in the generation of seizures. At the end of the 19th century and on two other
separate occasions in the 20th century, callosotomy was considered as a
treatment for seizure disorders. Before 1900, less obviously around 1940, and
most clearly in the 1960s, these therapeutic considerations were stimulated by
animal experimentation. One theme of this chapter is the reciprocal interaction
of surgical therapy and laboratory experimentation: in particular, the most
recent therapeutic use of callosotomy has been accompanied by widespread
physiological and psychological interest in this conspicuous brain structure. In
this chapter we consider first a brief history of studies of the corpus callosum.
Then follows a chronological account of interest in callosotomy as a treatment
for epilepsy. (Henry Gray, et al , 1995)
2-3-3 Studies of Callosal Function
Studies of the corpus callosum were first undertaken by the Humoral
Anatomists. These were the writers of antiquity whose concepts of brain
function emphasized the contents of the brain cavities and the flow of various
fluids such as air, phlegm, cerebrospinal fluid, and blood. For them, the corpus
37
callosum seemed largely a supporting structure. This view persisted for a
millennium. Even that originally (Renaissance genius, Andreas Vesalius,
1514-1564), believed that the corpus callosum served mainly as a mechanical
support, maintaining the integrity of the various cavities. In 1543, he wrote:
There is a part [whose] external surface is gleaming white and harder than the
substance on the remaining surface of the brain. It was for this reason that the
ancient Greeks called this part "tyloeides" ["callosus" in Latin] and, following
their example, in my discourse I have always referred to this part as the corpus
callosum. If you look at the right and left of the brain, and also if you compare
the front and rear, the corpus callosum is observed to be in the middle of the
brain; Indeed, it relates to the right side of the cerebrum more than to the left;
then it produces and supports the septum of the right and left ventricles; finally,
through that septum it supports and props the [fornix] so that it support it, so as
to not collapse and, to the great detriment
( observe and control as well as
integrate with the other side ) of all the functions of the cerebrum, crush the
cavity common to the two [lateral] ventricles of the cerebrum.(D.W.Roberts , et
al , 1995).
In the 17th century, the "traffic anatomists" took a major step forward. It was at
about the time of (Thomas Willis ,1621-1675) that anatomists began thinking
more in terms of a traffic or communication between the more solid parts of the
brain. This view became quite explicit in the statement of (Felix ,1748-1794)
who wrote in 1784: "It seems to me that the commissures are intended to
establish sympathetic communications between different parts of the brain, just
as the nerves do between different organs and the brain itself.
For over two centuries, beliefs about callosal function consisted almost solely of
inferences from its central location, widespread connections, and large size
(larger than all of those descending and ascending tracts, taken together, that
connect the cerebrum with the outside world). Among others, (Willis, François
de la Peyronie ,1678-1747), and (Giovanni Lancisi ,1654-1720) thought the
38
corpus callosum a likely candidate for "the seat of the soul," or they used some
other expression intended to cover that highest or ultimate liaison
(communication) which brings coherent, vital unity to a complex assemblage.
The observations of the early anatomists have often been supported by
subsequent anatomical observations, including the large number of callosal
fibers (at least 200 million of them). Because the callosal fibers interconnect so
much of the cerebral cortex, especially that cortex considered associative, it has
often been suggested that they serve some of the "highest," most educable, and
characteristically human functions of the cerebrum.
Inference of function from observable structure is time-honored and productive;
however, such inference has its limitations. The physiological evidence has only
partially sustained anatomical inference. We now know from various
observations (notably the split brain) that the corpus callosum is indeed an
important integrative structure; we also know that it is neither sufficient nor
indispensable, providing only one of a number of integrative mechanisms.
(D.W.Roberts , et al , 1995).
That the corpus callosum is not the exclusive "seat of the soul" is evident from
the apparent normality in social situations of patients who have had complete
callosotomies.That it is an important integrating mechanism is clear from the
peculiarities of such patients. These include, among other things, a unilateral
tactile anomia, a left hemialexia. And a unilateral apraxzia. That is, for the
right-hander with complete callosotomy, there is an inability to name aloud
objects felt with the left hand, an inability to read aloud written material
presented solely to the left half-field of vision, and an inability to execute with
the left hand actions verbalIy named or described by the examiner. The apraxia
usually recedes in a few months, whereas the hemialexia and unilateral anomia
persist for years. Such deficits are now readily demonstrable in individuals who
have had surgical section of the corpus callosum. But these deficits were first
39
recognized in patients with vascular disease that caused very complex and
evolving syndromes. (D.W.Roberts , et al , 1995).
In the closing decades of the 19th century ,there emerged a group of
neurologists whose discoveries and formulations are still at the core of current
clinical knowledge. Among them were Carl (Wernicke,1848-1905), (Hugo
Liepmann,1863-1925), (J. Jules Dejerine,1849-1917), and (Kurt Goldstein
,1878-1965), who interpreted various neurological symptoms as resulting from
disconnection, including interruption of information flow through the corpus
callosum.
The concept of apraxia was developed by Liepmann expressly to describe a
patient who could carry out commands with one of his hands but not with the
other. In 1908, Liepmannand Maas 26 described a right-handed patient whose
callosal lesion caused a left apraxia as well as a left-handed agraphia (an
inability to write) in the absence of aphasia. These disabilities have
subsequently been observed many times. Unilateral apraxia and unilateral
agraphia are not always present, and they may subside when a stroke victim
progressively recovers, but they remain among the cardinal signs of callosal
interruption.
Liepmann considered the corpus callosum instrumental in most left-hand
responses to verbal command: the verbal instruction was comprehended only by
the left hemisphere, and the left hand followed instructions delivered not by a
directly descending pathway (which we now call "ipsilateral control") but by a
route involving callosal interhemispheric transfer from left to right and then by
right hemisphere control of the left hand (what we now call "contralateral
control"). (D.W.Roberts , et al , 1995).
Necessarily then, callosal interruption would result in an inability to follow
verbal commands with the left hand, although there would be no loss of
comprehension (as expected from a left hemisphere lesion) and no weakness or
incoordination of the left hand (as could result from a right hemisphere lesion).
41
This view was largely ignored or rejected (particularly in the English-speaking
countries) for nearly half a century.
(Norman Geschwind ,1926-1984) suggested that there was a widespread
revulsion against attempts to link brain to behavior, associated with the rise of
psychoanalysis (personal communication). He had another sociological
explanation:
Henry Head had been shrewd enough to point out that much of the great
German growth of neurology had been related to their victory in the FrancoPrussian war. He was not shrewd enough to apply this valuable historical lesson
to his own time and to realize that perhaps the decline of the vigor and influence
of German neurology was strongly related to the defeat of Germany in World
War I and the shift of the center of gravity of intellectual life to the Englishspeaking world, rather than necessarily to any defects in the ideas of German
scholars. 19 As Harrington put it, 2l ways of thinking about the brain (i.e.,
laterality and duality) which seem natural enough now had "vanished from the
working world view" for nearly 50 years. She has made available in scholarly
detail the popularity of these ideas (laterality and duality) in the 19th century,
and their eventual re-emergence in the 1960s. Chapter 9 of Harrington's book2l
is devoted to the causes of this long eclipse. She was particularly critical of
(Henry Head ,1861-1940), whose highly selective reference to John Hughlings
Jackson, she wrote, "borders on intellectual dishonesty."
Besides the sociological aspects, other factors were involved. There was
widespread reluctance to consider callosal disconnection as the efficient cause
of deficits such as unilateral apraxia or hemialexia occurring in patients with
lesions (e.g., tumors or infarctions) involving the corpus callosum. This
reluctance developed in large part because surgical interruption of the corpus
callosum had not been found to cause the same deficits. Walter (Dandy ,18861946) went so far as to say in 1936: "The corpus callosum is sectioned
longitudinally; no symptoms follow its division. This simple experiment puts an
41
end to all of the extravagant hypotheses on the functions of the corpus callosum.
Even more persuasive were the negative tests performed by (Andrew J.
Akelaitis ,1904-1955)1 on patients who had callosal section. By the end of the
1950s, Fessard summarized the view that was then generally accepted: "There is
a great deal of data showing [that] section of important associative white tracts
such as the corpus callosum does not seem to affect mental performances. Other
similar observations in man or animals are now accumulated in great number
and variety. (D.W.Roberts , et al , 1995).
We now realize that most of the negative findings resulted from two sources:
1. When surgical section of the commissures is incomplete, a remarkable
capacity for maintaining cross-communication between the hemispheres may be
retained with quite small commissural remnants, particularly when the part
remaining is at the posterior end of the corpus callosum (in other words, the
splenium). (D.W.Roberts , et al , 1995).
2. Negative findings often result from the use of inappropriate or insensitive
testing techniques. What one finds depends on what one looks for; although
Dandy" said that callosal section produces no observable deficits, among his
own patients was one reported by Trescher and Ford to have hemialexia.
Essential to the resurrection of the callosal disconnection view was the ability to
observe
repeatedly
and
appropriately
under
controlled,
prospective
circumstances the results of callosotomy in humans. This was facilitated by the
use of complete callosotomy as a treatment for epilepsy, which, in turn, had
been made possible by cat and monkey experiments beginning in the 1950s.
Forty years of experimentation with laboratory animals and 30 years of
experience with callosotomized humans have by now firmly established the
principal features of callosal section and facilitated the more precise
interpretation of deficits following naturally occurring lesions. (D.W.Roberts ,
et al , 1995).
42
The impression is gained from this small number of observations that the type
of case in which section of commissural fibers in the corpus callosum is most
favorable is the one in which a large cortical or subcortical scar exists.
2-3-4 The Corpus Callosum and Epilepsy
The famous experiments of Gustav Fritsch (1838-1891) and Eduard Hitzig
(1838-1907) in 1870 showed that there was a limited region of the cerebral
cortex (the "motor cortex"), electrical stimulation of which resulted in
movements of the contralateral limbs."," In two of their dogs, removal of the
electrically excitable cortex resulted in subsequent incoordination of the
contralateral limbs. In another two dogs, tetanization caused "epileptic attacks"
beginning first in the contralateral limbs and then becoming generalized. The
generalization of the "epileptic attacks" could be interpreted, in retrospect, as
due to transmission across the corpus callosum. ( Alexander G. et al 2013)
A next step was taken by Bubnoff and Heidenhain in 1881. They stimulated the
white matter exposed by ablation of the motor cortex. This stimulation could
produce convulsive movements in the unparalyzed ipsilateral limbs. They
concluded that excitation had spread across the corpus callosum to involve the
motor cortex of the opposite hemisphere. A few years later, in 1886, (Sir Victor
Horsley,1857-1916) lectured on the effectiveness of cutting the corpus callosum
to prevent the spread of seizures. He recognized (as had Bubnoff and
Heidenhain) that subcortical circuits could maintain convulsive activity once it
began, but emphasized the role of cerebral cortex in the initiation of
convulsions. ( Alexander G. et al 2013)
In succeeding decades, the possible role of the corpus callosum in seizure
spread was studied in experimental animals by many other investigators. When
Spiegel" reviewed the physiology of epilepsy in 1931, he emphasized the
common finding that generalized convulsions could occur after the corpus
callosum connections had been severed. His own experiments included section
of all crossing fibers down to the rhombencephalon and he stated that "even
43
after this operation, we could observe that general clonic convulsions developed
following one-sided cortical stimulation." He also described experiments with a
sagittal section of the rhombencephalon in the midline, again with generalized
convulsions being possible from stimulation of one hemisphere. Evidently,
generalization can occur through fibers that cross the midline at several levels.
Many years before, (John Hughlings Jackson ,1835-1911) had asserted that
whatever its behavioral manifestations, seizure activity was characterized by an
excessive discharge (we now call it "hypersynchronous and self-maintaining")
of nerve cells. In 1878, he wrote: "A convulsion is but a symptom, and implies
only that there is an occasional, an excessive, and a disorderly discharge of
nerve tissue on muscles. Elsewhere he wrote: Scientifically, I should consider
epilepsies on the hypothesis that the paroxysm of each is dependent on a sudden
temporary excessive discharge of some highly unstable region of the cerebral
cortex. There is, in other words, in each epilepsy a "discharging lesion" [which]
leads to secondary discharge of healthy cells in other centers. This assertion met
with considerable resistance at the time but was ultimately confirmed by
electroencephalographic (EEG) studies. These included animal experiments by
Moruzzi, 28 among others. Moruzzi observed that epileptiform EEG activity
induced by electrical stimulation in one hemisphere promptly appeared in the
other with a latency consistent with the conduction speed of callosal fibers, and
this spread could be prevented by callosotomy. However, this finding did not
negate the possibility of spread via other routes.
The multiplicity of routes for seizure spread rendered unattractive the idea of
cutting the corpus callosum for treatment of epilepsy, particularly in view of the
technical difficulties which this would involve. The feasibility of cutting the
corpus callosum was subsequently emphasized in 1936 by Dandy, who used this
approach to reach midline tumors. But neither he nor others of the time
recommended callosotomy for epilepsy. ( Alexander G. et al 2013)
44
The first callosotomies for epilepsy were reported in 1940 by Van Wagenen and
Herren; they operated on their first case on February 6, 1939. (William P. Van
Wagenen ,1897-1961) was at that time Chief of Neurosurgery at the University
of Rochester, Strong Memorial Hospital. The rationale given for this procedure
was their observation of two cases in which a callosal tumor had lessened
seizure frequency and two cases of vascular insult that stopped the seizures
altogether. Their paper contained no references; hence it is not clear if the
authors knew of Spiegel's 1931 report 39 or the material that he summarized. It
seems less likely that they were aware of Mortuzzi's investigations in the mid1930s. Nor is it clear if they were aware of the work of Erickson. In 1940,
(Theodore Erickson ,1906-1986)16 had performed experiments on monkeys
showing a role of the corpus callosum in seizure spread, and his report was
published in the preceding volume of the same journal. One might assume that
Erickson's animal experiments at the Montreal Neurological Institute were
known to Van Wagenen, since the neuroscience community was quite small in
those days. Moreover, both attended meetings of the American Neurologic
Association. Robert Joynt,25 who arrived at the University of Rochester as
Chairman of Neurology in 1966, hasemphasized that the Van Wagenen series
was undertaken "solely on clinical observations [which were personally made]
by the two authors." Joynt focused special attention on the summary of the Van
Wagenen-Herren paper. Parts of the summary are worth repeating here because
their conclusions have remained largely correct after more than 50 years. (
Alexander G. et al 2013)
Van Wagenen and Herren summarized their first 10 experiences with
callosotomy as follows:
The impression is gained from this small number of observations that the type
of case in which section of commissural fibers in the corpus callosum is most
favorable is the one in which a large cortical or subcortical scar exists .
( Alexander G. et al 2013)
45
Whether section of various commissural pathways to prevent the spread of an
epileptic wave is indicated for patients having multiple irritable fociis a matter
for future study ... the observation on patients having jacksonian seizures on the
right side after section of the corpus callosum on one occasion and on the left
side on another suggests that there are at least bilateral foci from which seizures
may originate. ( Alexander G. et al 2013)
The inhibitory effect of the cortex of one hemisphere on the activity of the other
must also be considered seriously ... it may be that in certain instances the
cortex of one hemisphere may inhibit abnormal activity of an abnormal zone
and that section of commissural pathways is contraindicated. ( Alexander G. et
al 2013)
Section of the commissural pathways contained in the corpus callosum may be
carried out without any untoward effect on the patient. Such a section may serve
to limit the spread of an epileptic wave to the opposite hemisphere. When such
limitation occurs, the patients do not seem to lose consciousness or have
generalized convulsions.
Although Van Wagenen and Herren seemed pleased with their results, no one
else took up the operation. This may have been in part because of the onset and
continuation for 5 years of World War 11, or longer term outcomes may have
been unfavorable and generally known although unpublished (see the section on
personal recollections). An important factor was the growing conviction,
reaching a peak in the 1950s that the reticular formation and its rostral targets in
the thalami are of particular importance for seizure spread. As Penfield and
jasper stated in one of the great classics of epileptology: It seems reasonable to
assume, therefore, that generalization of the motor seizure does not take place
by spread of excitation through cortical circuits. It must spread through the
more closely interrelated neuronal network of the higher brain stem, in a
centrencephalic system with symmetrical functional relationships to both sides
of the body."'
46
The irrelevance of callosal transmission for generalization of unilateral seizures
was also suggested by the occasional recurrence of generalized convulsions in
humans with hemispherectomy.Indeed, in a few experiments generalized
convulsions could be produced by Van Harreveld in dogs subsequent to
bilateral decortication .
In spite of the foregoing, a number of other considerations discussed below
suggested the possibility of improvement of otherwise untreatable seizure
disorders in carefully chosen cases. Briefly, the reintroduction in 1962 of
callosotomy together with anterior and hippocampal commissurotomy as a
treatment for medically intractable epilepsy was stimulated and indeed made
possible by animal experimentation involving similar procedures in cats and
monkeys (e.g., Sperry and Myers) . Because of the remarkable improvement of
two patients treated by Bogen et al, we continued to offer the operation. A few
years later we briefly reported our rewarding results in nine of 10 cases, each
having at least 2 years follow up, concluding: "It thus appears that the
combination of cerebral commissurotomy plus postoperative medication has
limited propagation of seizure activity from a cortical focus. The improved
status of these patients made possible their participation in a long and still
continuing series of neuropsychological investigations. These investigations,
which contributed to Roger Sperry's Nobel Prize in 1981, supported two
generalizations: that there was incomplete but substantial hemispheric
independence, and complementary hemispheric specialization. In a classic
paper, Sperry wrote: Although some authorities have been reluctant to credit the
disconnected minor hemisphere even with being conscious, it is our own
interpretation based on a large number and variety of nonverbal tests, that the
minor hemisphere is indeed a conscious system in its own right, perceiving,
thinking,
remembering,
reasoning,
willing,
and
emoting,
all
at
a
characteristically human level, and that both the left and the right hemisphere
47
may be conscious simultaneously in different, even in mutually conflicting,
mental experiences that run along in parallel. ( Alexander G. et al 2013)
Though predominantly mute and generally, inferior in all performances
involving language or linguistic or mathematical reasoning, the minor
hemisphere is nevertheless clearly the superior cerebral member for certain
types of tasks. Largely they involve the apprehension and processing of spatial
patterns, relations, and transformations. They seem to be holistic and unitary
rather than analytic and fragmentary, and orientational more than focal, and to
involve concrete perceptual insight rather than abstract, symbolic, sequential
reasoning. However, it yet remains for someone to translate in a meaningful
[i.e., physiological] way the essential right-left characteristics. ( Alexander G.
et al 2013)
1) The data, as well as what they implied, were sufficiently dramatic to attract
increasing media attention. Much of this was hastily written and often
sensationalized. According to the New Yorker magazine of November 8, 1976
(p 36), "The corpus callosum is an inch long An article in the New York Times
Magazine on September 9, 1973, included an artist's drawing of a split-brain
patient wielding a hatchet in the left hand which was being restrained by the
right hand. Less esteemed media outlets were worse, and there were
innumerable cartoons. The media pushed the popularity of the "right brain/left
brain" story to fad proportions, reaching an almost frenzied peak by 1980. This
led not only to simplistic degradation, probably inevitable with popularization,
but also to exploitation. Commercially motivated entrepreneurs promised to
educate people's right hemispheres in short order, sometimes even overnight,
ignoring the lengthy, arduous training necessary for mature competence.
This was followed by a reaction or backlash, much of which involved the
debunking of extravagant claims." Some of it, however, was more revisionist;
that is, some writers challenged the basic observations. A notable example is the
recent explicit rejection of hemispheric specialization by Efron "I have offered
48
elsewhere 5 some tentative evaluations of these events, which provide an
example of how 20th century neurosurgery has influenced both academic and
popular psychology".
Our reports of therapeutic success with callosotomy were followed by a few
others (Luessenhop et al). However, wider acceptance of this procedure was
made possible only by the sustained effort during the decade of the 1970s of
Donald H. Wilson, and coworkers, particularly Alexander Reeves, at Dartmouth
Medical 17School. By 1982, at the Dartmouth conference organized by Wilson
and Reeves, the use of callosotomy for epilepsy was reported from six more
clinical centers. There had also been a burgeoning of experimental studies,
many of them presented at that conference. Both the clinical and experimental
contributions were subsequently included in a book edited by Reeves. During
the 1980s, callosotomy (either complete or more often partial) became an
established procedure. In the words of Spencer et al:
Over the past decade, corpus callosum section has become a widely accepted,
relatively safe, clearly needed, broadly practiced, and continually evolving
addition to the medical treatment of certain types of severe and uncontrolled
seizures in certain types of patients who are not candidates for respective
procedures. Over a span of about 30 years, during which callosotomy came to
be more favorably viewed as a treatment for epilepsy, increased familiarity with
both the anatomy and the physiology of the corpus callosum has encouraged the
use of partial callosotomy as an approach to the third ventricle and other
midline structures.
Concluding Remarks about physiology
The multifactorial causation of postcallosotomy mutism affords a measure of
our ignorance, representing as it does the difficulties in predicting the likelihood
of this usually transient but nonetheless distressing malfunction. On the other
hand, the very existence of this riddle affords an opportunity for someone to
unravel it. Likewise, the lack of replicate signs or symptoms from section of the
49
anterior two thirds of the corpus callosum represents a territory still unknown
and awaiting exploration.
That the transcallosal approach to the third ventricle is largely without
obligatory physiological cost is both a boon to the operator and a challenge to
the scientist. Neurosurgeons have historically been both therapeutic and
investigative, and we can expect that continued exploitation of the transcallosal
approach will benefit our patients both at the time of treatment and by
augmenting our understanding of what Bremer once called, "the highest and
most elaborate activities of the brain."
Summary of Corpus Callosum physiology:
The corpus callosum is a thick band of nerve fibers that divides the cerebrum
into left and right hemispheres. It connects the left and right sides of the brain
allowing for communication between both hemispheres. The corpus callosum
transfers motor, sensory, and cognitive information between the brain
hemispheres.
Function:
The corpus callosum is involved in several functions of the body including:

Communication Between Brain Hemispheres

Eye Movement

Maintaining the Balance of Arousal and Attention

Tactile Localization
Fig (2-21) :Corpus Callosum. Credit: Gray's Anatomy
o.tqn.com/d/biology/1/G/q/z/corpus-collosum.jpg
51
2-4 pathology
2-4-1 Disorders of corpus callosum
2-4-2 Outline:
Disorders of corpus callosum include Agenesis of corpus callosum , Tumors ,
Lipoma, Glioblastoma multiforme, Lymphoma, Juvenile pilocytic astrocytoma ,
Demyelinating
diseases,
Multiple
sclerosis
Progressive
multifocal
leukoencephalopathy, Marchiafava-bignami disease, Vascular which include
Infarction and Arteriovenous malformations , Trauma , Miscellaneous lesions ,
Lesions of corpus callosum in psychiatric diseases .
2-4-3AGENESIS OF CORPUS CALLOSUM
Agenesis of the corpus callosum (ACC) is a rare birth defect (congenital
disorder) in which there is a complete or partial absence of the corpus callosum.
The development of the fibers that would otherwise form the corpus callosum
become longitudinally oriented within each hemisphere and form structures
called Probst bundles. In addition to agenesis of the corpus callosum, other
congenital callosal disorders include :
1. Hypogenesis (partial formation), 2. Dysgenesis (malformation) of the corpus
callosum, 3. Hypoplasia (underdevelopment) of the corpus callosum. Diagnosis
of callosal disorders can be diagnosed only through a brain scan; they may be
diagnosed through an MRI, CT scan, prenatal ultrasound, or prenatal MRI.
Cause of agenesis of the corpus callosum:
is caused by disruption to
development of the fetal brain between the 3rd and 12th weeks of pregnancy. In
most cases, it is not possible to know what caused an individual to have ACC or
another callosal disorder. However, research suggests that some possible causes
may include chromosome errors, inherited genetic factors, prenatal infections or
injuries, prenatal toxic exposures, structural blockage by cysts or other brain
abnormalities, and metabolic disorders. Signs and symptoms vary greatly
among individuals some characteristics common in individuals with callosal
disorders include 1. Poor motor coordination, 2. Delays in motor milestones
51
such as sitting and walking, 3. Delayed toilet training, 4. Chewing and
swallowing difficulties 5. Vision impairments, 6. Hypotonia 7. Low perception
of pain. Researches: shown to have some cognitive disabilities (difficulty in
complex problem solving) and social difficulties (missing subtle social cues),
even when their intelligence quotient is normal. Other characteristics sometimes
associated with callosal disorders include seizures, spasticity, early feeding
difficulties and/or gastric reflux, hearing impairments, abnormal head and facial
features, and mental retardation. Associated syndromes like ACC can occur as
an isolated condition or in combination with other cerebral abnormalities,
including Arnold-chiari malformation, Dandy-walker syndrome, Andermann
syndrome (motor and sensory neuropathy), Schizencephaly (clefts or deep
divisions in brain tissue), Holoprosencephaly (failure of the forebrain to divide
into lobes.). Girls may have a gender-specific condition called Aicardis
syndrome, which causes severe mental retardation, seizures (infantile spasms),
abnormalities in the vertebra of the spine, and lesions (lacunae) on the retina of
the eye. ACC can also be associated with malformations in other parts of the
body, such as midline facial defects.The effects of the disorder range from
subtle or mild to severe, depending on associated brain abnormalities.
Treatment: There are currently no specific medical treatments for callosal
disorders; it usually involves management of symptoms and seizures if they
occur. Patients may benefit from a range of developmental therapies,
educational support, and services. Prognosis varies depending on the type of
callosal abnormality and associated conditions or syndromes.ACC does not
cause death in the majority of children. Mental retardation does not worsen.
Although many children with the disorder have average intelligence and lead
normal lives, neuropsychological testing reveals subtle differences in higher
cortical function compared to individuals of the same age and education without
ACC.
52
Tumors of the corpus callosum, especially those involving the anterior portion,
frequently cause psychiatric and behavioral symptoms. These include Catatonia,
Depression, Psychotic symptoms, and Personality changes. Definitive brain
imaging studies are indicated in psychiatric patients with new or pre-existing
psychiatric and behavioral symptoms accompanied by focal neurological
findings atypical presentation.
Lipoma: Intracranial lipomas are rare developmental lesions of the central
nervous system, which are usually asymptomatic and discovered incidentally.
They mainly occur in the region of the corpus callosum and the pericallosal
cistern, accounting for up to 65% of all intracranial lipomas and frequently
associated with callosal dysgenesis 2-year-old boy with Lipoma of corpus
callosum. Coronal T1-weighted MR image shows large well-defined
homogeneous midline mass lesion in region of corpus callosum with
characteristic bright signal of Lipoma. Note associated dysgenesis of corpus
callosum.
Fig (2-22) Lipoma of Corpus callosum
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Glioblastoma Multiforme is an extremely aggressive diffuse astrocytic tumor
commonly found in the upratentorial white matter of the cerebral hemispheres.It
is the most common primary brain tumor in adults, accounting for 25% of all
cases. Glioblastomas most commonly spread via direct extension along white
matter tracts, including the corpus callosum, although hematogenous,
subependymal, and cerebrospinal fluid spread can also be seen. When the
corpus callosum is affected, Glioblastoma Multiforme commonly displays a
characteristic bihemispheric involvement, resulting in a classic butterfly pattern.
Because the corpus callosum is relatively resistant to infiltration, Glioblastoma
Multiforme should be considered for any lesion crossing the corpus callosum.
A, Axial T1-weighted MRI. B, Axial T2-weighted MRI. C, Enhanced axial T1weighted image shows hypo intensity image shows hyper intensity MR image
shows Glioblastoma of the left parietal white matter extending across matter
that extends across corpus callosum. Corpus callosum with mass corpus
callosum, classic for effect on lateral ventricle. This may be Glioblastoma
Multiforme or lymphoma.
A
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54
Fig 2-23: Sagittal MRI with contrast of a Glioblastoma WHO grade IV in a
15-year-old boy.
http://upload.wikipeda.org/wikipedia/commous/c/co/glioblastoma:-MRsagittal-with-contrast.jpg
Fig 2-24 Coronal MRI with contrast of a Glioblastoma WHO grade IV in a
15-year-old boy
http://upload.wikipeda.org/wikipedia/commous/thumb/c/cb/glioblastoma:MR-control -with-contrast.jpg/230px-glioblastoma
Primary central nervous system lymphomas are rare aggressive neoplasms of
the brain, accounting for less than 2% of malignant primary brain tumors. They
are almost always of the B-cell non-Hodgkin’s type. Common locations include
the corpus callosum, deep gray matter structures, and the periventricular region.
Lymphomas differ from Glioblastoma Multiforme because they usually have
55
less peritumoral edema, are more commonly multiple, are less commonly
necrotic, are highly radiosensitive, and fre- quently temporarily respond
dramatically to steroid administration producing “vanishing lesions.”
Juvenile Pilocytic Astrocytoma is a distinct low-grade variant of astrocytoma.
They are usually well-circumscribed unencapsulated masses, with frequent cyst
formation, either microscopic or macroscopic. Most lesions commonly involve
the cerebellar vermis, cerebellar hemispheres, optic chiasm, hypothalamus, or
floor of the third ventricle. The corpus callosum is an uncommon location. The
solid portion of the tumor usually enhances, in contrast to most low-grade
infiltrative astrocytomas, which tend not to enhance astrocytoma. A, Sagittal
T1-weighted MRI shows well- circumscribed hypointense lesion in body of
corpus callosum. B, Axial T2-weighted MRI shows that lesion is hyper intense.
C, Enhanced coronal T1 - weighted MR image shows marked contrast
enhancement of lesion.
Fig 2-25 Coronal MRI contrast of a Glioblastoma WHO grade IV in a 4year-old Girls with Pilocytic Astrocytoma
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Demyelinating Diseases : Multiple sclerosis is a demyelinating disease of
unknown cause that more commonly affects young women. Lesions
characteristically involve the periventricular white matter, internal capsule,
corpus callosum, and pons, although plaques can be found anywhere in the
white matter and less commonly even in gray matter. The lesions of the corpus
callosum can be focal or confluent nodular lesions and tend to affect the
callosal–septal interface, which is the central inferior aspect of the corpus
callosum. On MR imaging, the prevalence of lesions in the corpus callosum has
been reported to be up to 93% in the radiology literature. Atrophy of the corpus
callosum can coexist in long-standing multiple sclerosis, making the diagnosis
of corpus callosum lesions difficult. Enhancement is common in the acute stage.
Differentiation should be made from ischemia, trauma, and other demyelinating
processes on the basis of morphology, location, and the presence of concurrent
multiple sclerosis plaques in the periventricular region .
A
www.sehha.com/diseases/autommune/ms2/gif
57
B
Fig 2-26 Demyelinating Diseases , Multiple Sclerosis
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Progressive
Multifocal
Leukoencephalopathy
:
Progressive
multifocal
leukoencephalopathy is an uncommon progressive fatal demyelinating disease
that affects immunocompromised patients.The cause is a papovavirus , the
Creutzfeldt-Jakob virus. The lesions are usually multifocal and asymmetric,
most commonly affecting the subcortical white matter and corpus callosum. In
the corpus callosum, focal lesions can occur that enlarge and become confluent
as the disease progresses. Progressive multifocal leukoencephalopathy should
be considered in the differential diagnosis of space-occupying lesions in HIV
patients.The lack of enhancement and mass effect can act as features
differentiating this entity from others such as lymphoma or Glioblastoma
58
Fig 2-27 a 44-years old man with HIV
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Marchiafava-Bignami Disease:
Marchiafava-Bignami disease is a rare
demyelinating neurologic disorder, primarily affecting the corpus callosum. It
was first described in Italian wine drinkers and is thought to be due to chronic
and massive alcohol use. The central layers of the corpus callosum are affected,
with sparing of the dorsal and ventral layers (sandwich sign). The disease can
follow one of three clinical courses, a fulminate, acute form or subacute and
chronic forms. Acute affect the genu and the splenium, chronic affect the
body. Marchiafava-Bignami Disease A, Axial T2-weighted MR image shows
signal B, Sagittal T1-weighted MR image shows corpusabnormality of corpus
callosum and callosum atrophy (short arrow), which isperiventricular white
matter. Characteristic of chronic form. Involvement of central layers of corpus
callosum, indicated by hypointensity, with sparing of dorsal and ventral layers
results in the sandwich sign (long arrow).
59
Fig 2-28 Infracts involving the corpus callosum
Medblog.med/ink-uj.net/laurasmall/files/2012/07/vascular.jpg
Vascular: Infarction: Infarcts involving the corpus callosum are rare, in part
because the corpus callosum is a dense white matter tract and therefore is less
sensitive to ischemic injury than gray matter. The anterior and posterior cerebral
arteries provide the major blood supply of the corpus callosum via the
pericallosal artery and small penetrating vessels that run perpendicular to the
parent artery.
On MR imaging, infarcts have the same characteristics as strokes elsewhere,
with similar enhancement patterns. Differentiation of lacunar infarcts from other
entities such as trauma and demyelinating processes can be made by the
presence of concurrent infarcts in characteristic sites (centrum semiovale, basal
ganglia). With large-vessel ischemic events, the corpus callosum is usually
involved as part of a large vascular distribution .Infarction 59-year-old man
61
with infarct who presented with confusion 2 weeks later 6 weeks after initial
onset : well-defined that lesion (arrow) is presentation shows lesion of corpus
smaller and has that lesion (arrow) iscallosum genu. decreased in signal.
Arteriovenous malformations of the corpus callosum comprise 9–11% of all
cerebral arteriovenous malformations. Clinically, 84% of patients with these
malformations present with intracranial hemorrhage, most with intraventricular
hemorrhage. Most are supplied by both the anterior and posterior cerebral
arteries, and many have a bilateral blood supply. Drainage is mainly into the
internal cerebral vein or interhemispheric superficial veins. The MR imaging
characteristics are those of arteriovenous malformations elsewhere, with
serpentine flow voids noted through the corpus callosum and the ventricle and
frequently with evidence of intraventricular hemorrhage.
Arteriovenous
Malformations A, Sagittal T1-weighted MR image shows
B, Axial T2-
weighted MR image shows hemorrhage (arrows) and multiple flow
hyperintense lesion (arrow) with flow voids. voids in corpus callosum.
Fig 2-29 Infraction 59- years old a man with infract
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61
Trauma: The classic triad of diffuse axonal injury is that of diffuse damage to
axons at 1. The gray–white matter interface of the cerebral hemispheres, 2. The
dorsolateral aspect of the rostral brainstem, 3. The corpus callosum. The callosal
lesions most commonly involve the splenium, are usually eccentric in location,
and can involve a focal part or the full thickness of the corpus callosum. On MR
imaging, spin echo T2-weighted images and FLAIR sequences during the
sagittal plane are most sensitive in detecting small nonhemorrhagic lesions.
Hemorrhagic lesions are best seen on T2- weighted images during the first 4
days after injury and, after 4 days, are better seen on T1- weighted images.
Differentiation from other lesions such as ischemia should be made on the basis
of history and the location of the lesions in the corpus callosum 20-year-old
man with diffuse axonal injury 1 week after motor vehicle crash. A, Sagittal T1weighted MR image shows nonhemorrhagic hypointense lesion (arrow) of
corpus callosum. B, Axial proton density–weighted MR image shows
hyperintense lesion of corpus callosum. C, Sagittal T1-weighted MR image on
follow-up examination 10 days after B shows hemorrhagic lesion of corpus
callosum. D, Enhanced coronal T1-weighted MR image on follow-up
examination 10 days after B shows hemorrhagic lesion of corpus callosum, with
classic shearing-type lesion also seen at gray, white junction, both indicative of
diffuse axonal injury.
Miscellaneous Lesions in the corpus callosum, both diffuse and focal, have been
described in patients with long-standing hydrocephalus after shunting. Callosal
lesions and tectal neoplasms producing hydrocephalus have been seen in
patients with aqueductal stenosis. Patients with these lesions were thought to
have long-standing hydrocephalus before ventricular decompression. The exact
mechanism responsible for the production of these callosal lesions is unknown,
although they may be the result of ischemia with subsequent demyelination
caused by prolonged severe stretching of the corpus callosum from
ventriculomegaly and subsequent rapid decompression of the ventricles.
62
45-year-old
man
with
cystic
lesions
associated
with
long-standing
hydrocephalus, with multiple prior shunt revisions. Patient is asymptomatic
other than for headaches, which are probably due to mild hydrocephalus. A,
Sagittal T1-weighted MR image B, Axial T2-weighted MR image shows welldefined shows abnormal signal cystic lesions (arrows) of corpus (arrow)
throughout corpus callosum , which has persisted for many years.
Disconnection syndromes: After anterior cerebral artery occlusion with anterior
callosal infarction, the right hemisphere is deprived of verbal information; a
left-hand apraxia is seen, the patient cannot name unseen objects placed in the
left hand. Reciprocally, the right hand shows constructional apraxia. This is
termed the anterior disconnection syndrome. After occlusion of the left
posterior cerebral artery with infarction of the left occipital lobe and the
splenium (posterior portion) of corpus callosum, the language cortices of the
left hemisphere lose access to visual information: The left visual cortex is
damaged, as are the projections from the right visual cortex, which cross in the
splenium. – Thus, reading becomes impossible, although other language
functions are unaffected the syndrome of alexia without agraphia.
Disconnection syndromes Corpus callosotomy, which aims to prevent the
interhemispheric spread of seizures, results in a unique, transient disconnection
syndrome of Mutism, Apathy, Agnosia, Apraxia, Difficulty naming, Writing
with the nondominant hand. Gerstmann syndrome is characterized by four
primary symptoms: Dysgraphia/agraphia: deficiency in the ability to write
Dyscalculia/acalculia: difficulty in learning or comprehending mathematics
Finger agnosia: inability to distinguish the fingers on the hand Left-right
disorientation .This disorder is often associated with brain lesions in the
dominant (usually left) hemisphere
Lesions in psychiatric diseases ADHD, (Dyslexia): anterior part of corpus
callosum (Autism)
posterior part of corpus callosum OCD . Rostrum
OrbitoFrontal Cortex In childhood sexual abuse between 9 to 10 years and 14
63
to 16 years was associated with maximal affects on corpus callosum and frontal
cortex, respectively. PTSD smaller intracranial volume and corpus callosum
area. Lesions in Schizophrenia .Several observations are seen with the studies
on the corpus callosum in schizophrenia 1. Callosal pruning and myelination as
well as interhemispheric coherence continue to develop into early adulthood, a
factor that may be relevant to age of onset in schizophrenia 2. Impairments in
callosal transfer have been reported in patients, implicating alterations in
callosal connectivity; 3. Structural alterations in asymmetric perisylvian regions
linked by the callosum have been reported 4. Callosal myelination begins
prenatally and is susceptible to malnutrition, asphyxia and toxins of infectious
origin; also, these same events are linked with aberrant neuro-developmental
events in schizophrenia 5. The corpus callosum forms the roof of the superior
horns of the lateral ventricles, which are enlarged in schizophrenic patients. In
spite of evidence linking callosal abnormality to schizophrenia, imaging studies
assessing alterations in callosal morphometry as well as in other cortical and
subcortical structures have produced surprisingly mixed results.
2-5 imaging of corpus callosum
2-5-1 Ultrasonography of the corpus callosum:
2-5-1-1 Background:
The corpus callosum (CC) is the largest commissural pathway connecting the
two cerebral hemispheres. It develops relatively late during cerebral
ontogenesis, not assuming its definitive shape until 20 weeks of gestation, and
continues to grow well after delivery
[Malinger G, Pilu G.
Sonography of the fetal central nervous system, 2009]. Therefore, a proper
prenatal sonographic evaluation can be performed only after 20 weeks.
Ideally, the CC is assessed on ultrasound by direct visualization. It is a thin band
of white-matter fibers and is not depicted using a standard axial plane. It can be
seen in the coronal plane, but is only demonstrated in its entire length by using
mid-sagittal views, that represent the gold standard for diagnosing abnormalities
64
of this structure. Visualization of coronal and mid-sagittal planes requires
technical skill, and is not recommended in standard examinations of low-risk
pregnant patients. Reference ranges of fetal CC dimensions have been published
and can be used to assess normal and deviant development.
There is a general consensus that diagnosing CC abnormalities is difficult. In
standard examinations, absence of the CC may be detected because of either
indirect cerebral findings, such as ventriculomegaly, absence of the cavum septi
pellucidi or widening of the interhemispheric fissure, or associated extracranial
findings. The sensitivity of screening exams is, however, unknown, but is
probably limited. The interested reader is referred to a recent comprehensive
review.
2-5-1-2 Practical points:
Adequate demonstration of the CC in the second trimester can often be achieved
by standard transabdominal ultrasonography. However, in vertex fetal
presentation, a transvaginal scan with a high-frequency transducer provides
better resolution. In breech presentation, a transfundal approach is the only
possibility. In coronal and mid-sagittal views, the CC appears as a thin anechoic
space, bordered superiorly and inferiorly by echogenic lines. The mid-sagittal
view is certainly the most useful view. The ultrasound beam crosses the large
midline acoustic window, formed from anterior to posterior by the frontal or
metopic suture, the bregmatic fontanel and the sagittal suture, and this allows
good resolution of the brain structures of the midline. For a proper assessment
of the CC, good-quality two-dimensional (2D) gray-scale imaging is essential
and is generally sufficient. Color Doppler may, however, play a complementary
role, particularly in early gestation. In cases of difficult visualization, threedimensional (3D) ultrasound may be helpful.
2-5-1-3 Two-dimensional ultrasound:
Two practical approaches may be of help in order to achieve adequate
visualization of the CC: This approach is usually feasible transabdominally.
65

Obtain a standard mid-sagittal view of the fetal profile (Figure 2-5-1 a).

Angulate the transducer in order to use the acoustic window of the frontal
suture and the anterior fontanel, thus demonstrating the CC (Figure 2-51 b).

Fine side-to-side movements may be needed in order to achieve an ideal
image of the CC.
Figure 2-30. Coronal approach. Coronal section of anterior horns of lateral
ventricles and cavum septi pellucidi (arrow), with the latter oriented
strictly vertically. The transducer is then rotated 90°, obtaining a midline
brain section and visualizing the corpus callosum.
www.researchgate.net/ figure/236643821_figure-Figure-2This approach is feasible both transabdominally and transvaginally.

From a coronal section through the anterior fontanel, obtain a coronal
section of the anterior horns of the lateral ventricles and the cavum septi
pellucidi. The latter should be oriented as close to vertically as possible,
with the anterior horns on the same horizontal level (Figure 2-5- 2).

Rotate the transducer 90°, obtaining the mid-sagittal plane of the fetal
brain.

Fine side-to-side movements may be needed in order to achieve an ideal
image of the CC.
66
Figure 2-31. Color Doppler demonstration of cerebral circulation (midsagittal view) in a normal fetus at 20 weeks' gestation: the pericallosal
artery (arrow) highlights the corpus callosum.
www.researchgate.net/ figure/236643821_figure-Figure-2-Fig3Color Doppler visualization of the pericallosal artery (Figure 2-5-3)
Once the mid-sagittal plane of the fetal brain has been obtained, applying color
Doppler will demonstrate the course of the pericallosal artery. This may be
helpful, particularly in early gestation and in dubious cases. Proper adjustment
of pulse repetition frequency (main cerebral arteries have velocities in the range
of 20–40 cm/s during intrauterine life) and signal persistence enhances
visualization of small vessels.
Figure 2-32. Three-dimensional imaging. Axial view at the level of the
biparietal diameter (left) and reconstructed orthogonal plane showing the midsagittal view (right).
www.researchgate.net/ figure/236643821_figure1-Figure-4Three-dimensional assessment of the corpus callosum (Figure 2-32)
The main advantage of 3D imaging is the possibility of obtaining a ‘virtual’
mid-sagittal plane reconstructed from an axial approach, thus avoiding the need
67
to align the transducer with the midline cranial sutures. However, direct 2D
visualization allows images of much superior quality. Furthermore, 3D
ultrasound only allows visualization of the external contour of the CC and
therefore does not allow identification of abnormalities of CC thickness
(Malinger, et al 2006).
This approach is usually feasible transabdominally.

Obtain a standard axial view of the head at the level of the biparietal
diameter, with the intersection point of the planes positioned in the cavum
septi pellucidi.

Activate the volume contrast imaging (VCI) 3D mode to display the Band C-planes of the fetal head.

The CC should be visible in the C- or orthogonal plane which displays
the reconstructed mid-sagittal view of the fetal brain.

The intersection point may need to be moved towards either wall of the
cavum septi pellucidi to optimize the image of the CC.
2-5-2 CT/ MRI of the corpus callosum:
The usual morphological MRI sequences include a sagittal T1 or T2 (fluidattenuated inversion recovery ((FLAIR)) weighted plane, as well as DTI
reformatting images for an optimal study of the CC, were implemented.
MRI is the modality of choice for the study of the CC. As a densely packed
white matter structure, the CC is visualised with a high signal in T1 weighted
imaging (WI) and a low signal in T2 images. Sagittal plane images provide an
overview of the structural integrity and extent of development of the CC,
whereas in coronal images we can better evaluate its relationship to the cerebral
hemispheres.
Complete assessment of CC pathologies is facilitated by the acquisition of the
following sequences: T1 WI, fast spin-echo (FSE) T2 WI, as well as FLAIR
sequences and volume acquisition sequences with high resolution. New
techniques such as DTI have further expanded our capability to visualise the
68
organisation and orientation of the axonal pathways of the CC with tractography
and quantitatively with the use of anisotropic indices of diffusion such as
fraction anisotropy (FA) maps, permitting a better comprehension and analysis
of the CC microstructure.
The use of susceptibility-sensitive sequences (susceptibility-weighting imaging
((SWI)) plays an important role in the assessment of traumatic injury and other
pathologies of the brain resulting in the deposition of blood products or calcium,
including pathologies affecting the CC. Vascular ((three-dimensional (3D) timeof-flight (TOF)) sequences, on the other hand, are essential in cases of
ischaemic or haemorrhagic lesions.
Images after contrast media enhancement are not necessary for the study of
malformations or traumatic pathologies of the CC.
If a viral infection is suspected, the MRI study, including perfusion sequences,
should be repeated within 48–72 h after the initial study in order to confirm the
diagnosis.
CT imaging is important for the diagnosis of CC lipomas and other pathologies
with calcium deposition and can also be useful for the diagnosis of tumour,
haemorrhage or infarction; CT angiography is essential for the diagnosis of
aneurysms responsible for haematomas, more commonly situated in the anterior
part of the CC.
69
2-6 Previous Studies
Study (1) : Measurement of the corpus callosum using magnetic resonance
imaging in the north of iran. (Mohammadi MR1 et al 2011 . Iran )
This study was done to measure the size of CC and to identify its gender- and
age-related differences in the North of Iran
The size of CC on midsagittal section was measured in 100 (45 males, 55
females) normal subjects using magnetic resonance imaging (MRI) admitted to
the Kowsar MRI center in Gorgan-Northern Iran. Longitudinal and vertical
dimensions of the CC, longitudinal and vertical lengths of the brain and the
length of genu and splenium were measured. Data were analyzed by student's
unpaired t test, ANOVA and regression analysis.
The anteroposterior length and vertical dimension of the CC, the length of genu
and splenium were larger in males than in females, but these differences were
not significant. The anteroposterior and vertical lengths of the brain were
significantly larger in males than in females (P < 0.05). The length of CC
increased with age and regression equations for predicting age were derived
from the length of the CC. There was also a positive significant correlation
between the anteroposterior length of the CC and the length of the brain and
vertical dimension of the CC
Study (2)
Sex differences in corpus callosum size: relationship to age and intracranial
size
) Sullivan,Margaret J et al 2001. USA )
Report this study MRI to measure the body callosum in 51 healthy male. And
41 female in good health, stretched from the age of 22 years old to 71 years old,
The results of the measurement of body size callosum in males larger than
females
71
Study (3)
MR imaging of the corpus callosum: normal and pathologic findings and
correlation with CT. By : (Reinarz et al -1988).
The MR appearance of the corpus callosum was investigated in 80 normal
volunteers. Normal variations in appearance were recorded with regard to age,
gender, and handedness. The MR studies of 47 patients with a wide spectrum of
callosal disease were also reviewed. Abnormalities included trauma, neoplasia,
congenital abnormalities, vascular lesions, and demyelinating and inflammatory
conditions. The information provided by MR was compared with that obtained
from other radiographic examinations, particularly CT and angiography. In all
cases MR provided as much, and frequently more, information than was
obtained by other imaging techniques. We believe that MR should be the
primary imaging technique for the evaluation of corpus callosal disease.
Study (4)
The role of the corpus callosum in interhemispheric transfer of
information: excitation or inhibition?
(Bloom JS, Hynd GW,2009)
The corpus callosum is the major neural pathway that connects homologous
cortical areas of the two cerebral hemispheres. The nature of how that
interhemispheric connection is manifested is the topic of this review;
specifically, does the corpus callosum serve to communicate an inhibitory or
excitatory influence on the contralateral hemisphere? Several studies take the
position that the corpus callosum provides the pathway through which a
hemisphere or cortical area can inhibit the other hemisphere or homologous
cortical area in order to facilitate optimal functional capacity. Other studies
suggest that the corpus callosum integrates information across cerebral
hemispheres and thus serves an excitatory function in interhemispheric
communication. This review examines these two contrasting theories of
interhemispheric communication. Studies of callosotomies, callosal agenesis,
71
language disorders, theories of lateralization and hemispheric asymmetry, and
comparative research are critically considered. The available research, no matter
how limited, primarily supports the notion that the corpus callosum serves a
predominantly excitatory function. There is evidence, however, to support both
theories and the possibility remains that the corpus callosum can serve both an
inhibitory and excitatory influence on the contralateral hemisphere.
Study (5)
Corpus callosum: normal imaging appearance, variants and pathologic
conditions.
(Battal ,et al 2010)
Various types of lesions can occur within the corpus callosum (CC) which is a
white matter tract communicating corresponding regions of the cerebral
hemispheres. Magnetic resonance imaging is the modality of choice for the
evaluation of the CC. In addition, diffusion weighted imaging and diffusion
tensor imaging can provide additional information about the CC. The aim of
this study is to illustrate the imaging features of the corpus callosum and its
pathologies.
Study (6)
Dissociation between corpus callosum atrophy and white matter pathology
in Alzheimer's disease.
(Teipel et al , 2003)
OBJECTIVE:
To determine whether the size of the corpus callosum is related to the extent of
white matter pathology in patients with AD and age-matched healthy control
subjects.
METHODS:
White matter hyperintensity load and corpus callosum size were compared
between 20 clinically diagnosed AD patients and 21 age-matched healthy
control subjects. We investigated the effect of age and disease severity on
72
corpus callosum size and white matter hyperintensity, in addition to the relation
between corpus callosum areas and white matter hyperintensity load.
RESULTS:
We found significant regional atrophy of the corpus callosum in AD when
compared with control subjects, although the groups did not differ in their white
matter hyperintensity load. We further showed a region-specific correlation
between corpus callosum size and white matter hyperintensity in the control
group but not in AD patients. In the AD group, corpus callosum size correlated
with age and dementia severity, whereas white matter hyperintensity correlated
only with age.
CONCLUSION:
Corpus callosum atrophy in AD can occur independent of white matter
degeneration, likely reflecting specific AD pathology in projecting neurons.
73
CHAPTER THREE
Materials and Methods
3-1 Materials & tools:
3-1-1 Study population:
3-1-2 Inclusion criteria:
3-1-3 Exclusion criteria:
3-1 Machine used:
The study was conducted during the period from August 2013 up to February
2015 at Modern Medical Center, Khartoum-Sudan.MR examinations were
acquired on MRI Siemens Avanto 2010, 1.5 Tesla super-conducted magnet,
using T1-weighted, TR 450, Echo Time of 8.70, (multisection sagittal
conventional spin-echo sequence with a 5-mm section thickness, a 1.5-mm gap,
and a 256 X256 matrix, FOV 100.
3-2 Technique and method of measurements
A total of 100 Sudanese adults were included (50 were males and 50were
females) .All underwent MR examinations; Mean ages were 34.64±20.61.
For each study, the patients lied supine on the examination couch with their
head within the head coil .The head is adjusted so that the inter pupillary line is
parallel to the couch and the head is straight. The patients were positioned so
that the longitudinal alignment light lies in the midline and the horizontal
alignment light passes through the nasion, straps and foam pads are used for
immobilization. the sagittal image closest to the median sagital plane was used
to measure the (CC) antro-posterior distance (mm), genu thickness(mm), body
thickness (mm), splenum thickness (mm)and(CCI) . Patients with brain diseases
were excluded.
Figures (Gupta B, 2008) showed the points of measurements .Corpus callosum
index (CCI) was obtained on a midsagital Vol 22, No. 7;Jul 2015 147
[email protected]
74
T1weighted image, drawing a straight line at greatest anteroposterior diameter
of (CC) and a perpendicular at its midline, owing to points Aa, Bb and Cc.
(CCI) was found for each cases, from the calculated measurements by the
formula:- CCI= (Aa + Bb+ Cc) / Ac.
( 3.1) Material
( 3.1) Material:
75
3-3 Data analyses
All data were presented as mean± SD values. Data were analyzed by an
independent t test and by correlation analysis with the use of the SPSS (Inc.,
Chicago, Illinois version 16). A value of P˂0.05 was considered significant.
3-4 Ethical Consideration:
- No identification or individual details were published.
- No information or patient details will be disclosed or used for reasons
other than the study.
76
Chapter four
Results
Table (4-1): Distribution frequency and percentages according to Age
Age
Frequency
<10
11-20
21-30
31-40
41-50
>50
Total
Percent(%)
6
28
19
13
12
22
100
Mean age = 34.64 ± 20.62
6.0
28.0
19.0
13.0
12.0
22.0
100()
28%
30%
25%
22%
19%
20%
13%
15%
10%
12%
6%
5%
0%
<10
11.-20
21-30
31-40
41-50
>50
Fig (4-1) : Distribution frequency and percentages according to Age
Gender
Table (4.2) Distribution of ages and CCI and thickness genu and thickness body
and thickness splenum
Mean
Std.
Deviation
6.8971
Thickness
splenum
cc
16.7647
.5334
1.08507
2.45778
.08942
Age
Cc
length
Thickness
genu Aa
Thickness
body Bb
34.6400
75.7533
17.5447
20.61603
7.13869
2.13980
77
Cci
Table (4-3) : Distribution frequency and percentages according to Gender
Frequency
Percent(%)
50
50
100
50.0
50.0
100()
Male
Female
Total
Female
50%
Male
50%
Fig (4-2) by graph show gender details
Table (4.4) Results of male & Female ( mean + standard deviation )
Mean Brain AP sagtal
F
156.4882
M
156.4128
Total 156.4505
Mean Brain AP axial
F
161.3586
M
162.6688
Total 162.0137
Mean Brain Transverse axial
F
118.6380
M
121.0614
Total 119.8497
At P< 0.005
P- value
0.964
P- value
0.440
P- value
.046
78
Table (4-5a) Cc length, Thinkness genu Aa, Thickness body Bb, Thickness
splenum cc, CCI table for variables distribution according to age
Descriptives
Cc length
Thickness genu Aa
Thickness body Bb
Thickness splenum cc
CCI
N
Mean
Std. Deviation
Minimum
Maximum
<10
6
62.3417
5.33209
55.38
67.95
11-20
28
76.4650
4.96783
66.99
86.27
21-30
19
72.8816
8.41926
46.90
82.77
31-40
13
75.3285
4.41351
68.46
82.93
41-50
12
80.7308
6.34523
74.71
93.74
>50
22
78.5214
5.19045
68.06
89.73
Total
100
75.7533
7.13869
46.90
93.74
<10
6
15.0950
1.21535
13.18
16.17
11-20
28
17.3911
1.69320
14.64
19.74
21-30
19
18.2016
2.01853
15.10
21.52
31-40
13
18.4354
2.16693
15.06
21.77
41-50
12
18.0308
2.28717
14.60
21.19
>50
22
17.0495
2.36910
12.95
22.45
Total
100
17.5447
2.13980
12.95
22.45
<10
6
5.9500
.82808
4.89
6.83
11-20
28
6.6546
1.00530
4.24
7.81
21-30
19
7.4300
1.09337
5.16
9.69
31-40
13
7.2785
.74178
6.21
8.52
41-50
12
7.2975
1.09447
5.47
8.52
>50
22
6.5600
1.10860
4.44
9.44
Total
100
6.8971
1.08507
4.24
9.69
<10
6
12.0967
4.02092
4.78
15.48
11-20
28
16.4471
1.64376
13.52
20.72
21-30
19
16.9089
2.44413
8.88
20.40
31-40
13
17.3400
1.50774
15.14
19.91
41-50
12
18.2442
2.82233
15.37
23.46
>50
22
17.1705
1.59846
14.60
22.09
Total
100
16.7647
2.45778
4.78
23.46
<10
6
.5585
.03392
.51
.59
11-20
28
.5312
.03544
.45
.59
21-30
19
.5707
.03455
.51
.64
31-40
13
.5709
.04779
.48
.63
41-50
12
.4939
.16392
.00
.64
>50
22
.4964
.12151
.00
.62
Total
100
.5334
.08942
.00
.64
79
P -value
.000
.013
.005
.000
.028
Table (4-5b) Brain AP sagtal , Brain AP Length , Brain Ap axial , Brain
transvere axial table for variables distribution according to age
Descriptives
Brain AP sagtal
Brain AP Length
Brain Ap axial
Brain transvere axial
N
Mean
Std. Deviation
Minimum
Maximum
<10
6
143.5583
9.50841
131.86
159.21
11-20
28
158.4639
7.19019
142.05
170.60
21-30
19
154.8037
8.45380
135.30
171.90
31-40
13
156.0138
6.24504
146.68
168.47
41-50
12
158.5333
6.35491
149.52
174.72
>50
22
157.9482
8.52786
139.40
172.66
Total
100
156.4505
8.31206
131.86
174.72
<10
6
88.1383
6.45736
79.35
96.80
11-20
28
102.3900
10.89059
57.25
116.89
21-30
19
100.3595
5.66489
86.41
109.04
31-40
13
99.6877
6.80607
88.89
113.34
41-50
12
104.2100
4.56259
97.42
111.89
>50
22
99.1532
5.47430
85.62
108.93
Total
100
100.3041
8.18333
57.25
116.89
<10
6
146.4633
10.72192
126.28
158.37
11-20
28
161.9343
8.27932
145.27
176.18
21-30
19
161.1495
7.98706
141.64
178.96
31-40
13
160.9762
4.49775
153.03
169.02
41-50
12
165.2367
5.83370
159.38
176.83
>50
22
165.9573
6.51053
146.65
176.08
Total
100
162.0137
8.42502
126.28
178.96
<10
6
115.2117
7.76681
103.19
122.21
11-20
28
120.3046
5.89661
106.61
133.86
21-30
19
120.7411
5.73579
103.70
130.86
31-40
13
118.5831
5.61607
109.02
129.07
41-50
12
120.7475
5.70425
111.09
132.44
>50
22
120.0245
6.63216
109.01
134.67
Total
100
119.8497
6.09177
103.19
134.67
P value is considered significant at p = 0.005
81
P -value
.002
.002
.000
.437
Table (4-6) display table for variables distribution according to gender
Descriptives
Brain AP Length
CC length
Thickness genu Aa
Thickness body Bb
Thickness splenum
cc
CCI
Brainb AP sagtal
Brain Ap oxial
Brain transvere
oxial
N
Mean
Std. Deviation
Minimum
Maximum
Male
50
98.4952
9.41071
57.25
115.30
Female
50
102.1130
6.32938
84.18
116.89
Total
100
100.3041
8.18333
57.25
116.89
Male
50
74.2446
7.88008
46.90
89.73
Female
50
77.2620
6.01837
58.05
93.74
Total
100
75.7533
7.13869
46.90
93.74
Male
50
17.4778
2.11141
13.18
22.45
Female
50
17.6116
2.18718
12.95
21.77
Total
100
17.5447
2.13980
12.95
22.45
Male
50
6.8532
1.00520
4.89
9.69
Female
50
6.9410
1.16808
4.24
8.53
Total
100
6.8971
1.08507
4.24
9.69
Male
50
16.1350
2.47159
4.78
22.09
Female
50
17.3944
2.29928
8.88
23.46
Total
100
16.7647
2.45778
4.78
23.46
Male
50
.5334
.08674
.00
.62
Female
50
.5333
.09291
.00
.64
Total
100
.5334
.08942
.00
.64
Male
50
156.4128
8.40008
131.86
171.90
Female
50
156.4882
8.30821
135.30
174.72
Total
100
156.4505
8.31206
131.86
174.72
Male
50
162.6688
9.77553
126.28
178.96
Female
50
161.3586
6.85375
141.64
176.83
Total
100
162.0137
8.42502
126.28
178.96
Male
50
121.0614
6.27090
103.19
134.67
Female
50
118.6380
5.71455
103.70
131.46
Total
100
119.8497
6.09177
103.19
134.67
Model
1
B
Std. Error
(Constant)
.328
.072
Thickness genu Aa
.012
.004
Standardized
Coefficients
a. Dependent Variable: Cci
CCI =0.328 + 0.012 x 17.5
81
t
Sig.
4.585
.000
2.882
.005
Beta
.279
.034
.756
.010
.995
a
Unstandardized Coefficients
.026
.688
Table (4.7) coefficients of variable
Coefficients
P -value
.964
.440
.046
Fig (4-3) : shows the linear relation between thickness of Genu and CCI
82
Table (4.8 ) thickness body Bb
Coefficientsa
Unstandardized
Coefficients
Model
1
B
Std.
Error
(Constant)
.379
.056
Thickness
body Bb
.022
.008
Standar
dized
Coefficie
nts
t
Sig.
Beta
.271
a. Dependent Variable: Cci
CCI =0.379+0.022* Thickness body Bb
The relation between 83
CCI and Thickness
6.78
3
2.78
4
.000
.006
Chapter five
5-1 . DISCUSSION
Table [2] presented the data obtained from Sudanese population who were
examined by MRI sagital cuts for brain. The study results were presented for
the measurements related to age classes .The relations between the corpus
callosum (CC) parameters and Index with age was found to be significant at
p0.005.
That means that the age has an impact on the (CCI).
Age -related changes in (CC) morphology are controversial. Although many
studies have concluded that age- related callosal thinning is modest (Johnosn et
al 1994).Some studies have reported that it is statistically significant. ( Weis, et
al , 1993) Most cross sectional MRI studies of the (CC) fail to show age- related
shrinkage in adults from 3rd-7th decade.( Pfefferbaum , et al 1996) In contrast
one study have shown senescent effects over 3rd-8th decades. ( Doraiswamy , et
al 1991) Another has found age effects in elderly subjects especially those
exceeding 55 years. (Salat, et al 1997) Sullivan et al (Sullivan et al 2002)
reported statistically significant thinning of genu, body and splenium with age
on MRI study of mid sagittal brain sections, our results were similar to these
previous results.
As a result, we observed that (CC) is being developed significantly from
childhood to adult ages and in this growth, the gender does not make difference.
We concluded that in studies subjected to (CC) with respect to pathological
differences; it would be useful to consider the same age group records.
Knowledge of (CC) morphology and the gender as well as age- related changes,
thus is likely to be helpful in providing baseline data for the diagnosis of
presence and progression of disease.
The corpus callosum is the major anatomic and functional inter hemispheric
commissure in the human brain ( Tejal ,et al , 2003).Corpus callosum
dimensions, and sex-related differences have been of significance to
84
researchers, because they influence the performance of callosotomies in patients
with intractable epilepsy.
Reports describing numerous conflicting studies have been published with
respect to variations in the size of the corpus callosum relative to, gender and
age (Mourgela ,et al , 2007) Corpus callosum, being the major structure
connecting both the hemispheres, is likely to be affected by the physiologic as
well as pathological changes occurring in the cortical and sub cortical regions of
brain. Therefore different sub regions of the (CC) may be affected depending
upon the region of the brain involved, as fiber systems connecting
corresponding hemispheric regions pass through specific callosal sub regions.
Therefore, alteration in (CC) morphology may give a clue towards diagnosis of
specific disease processes. A knowledge of the normal (CC) morphology and
the gender as well as age related changes, thus is likely to be helpful in
providing baseline data for the diagnosis of presence of any pathological
changes The goal of this work was to provide gender-specific reference data
detailing the development of the corpus callosum based on MRI data from
hundred healthy Sudanese subjects aged 34.64±20.61years.
MR imaging enables the study of cerebral structure and function. Several neuroimaging studies have used the midsagittal area of the corpus callosum to show
differences in morphology related to sex (Habib , etal , 1991), aging (Hussein ,
et al 1991), and pathologic states (Laissy, et al 1993). The corpus callosum has
been shown to be altered in conditions such as schizophrenia (Suganthy , et al ,
2003) even when visual assessment of the MR images reveals normal findings.
Quantitative measures of the corpus callosum have been proposed as useful
indicators of disease progression. The results of most of these MR imaging
studies remain conflicting and controversial (Tejal , et all 2003)) The study
showed that the females (CC) length is greater than males, as seen in table (1),
adverse findings were noted by (Suganthy et al, 2003l) and (Elster et al,1993).
85
Several studies have found significant sex differences in the length, shape and
area of the corpus callosum of males and females; with females having larger
relative splenial width.[ 17-21] which is similar to our findings in Sudanese.
Justification for our study results was that the sexual dimorphism in (CC) might
be due to greater bi- hemispherical representation of cognitive functions in
females. [Sullivan, et al , 2001]. (DeLacoste-Utamsing and Holloway, 1982)
found the splenium to be larger in females. The previous studies results
concerning differences in absolute measures have infrequently been replicated
[19,20] Still the direction of non-significant absolute size differences in the
(CC) is not consistent, with some studies showing larger measures in males
[Witelsion, Demeter (1985,1988) others in females (Holloway, Deneberg , et al
1986,1991).The sexual dimorphism of the human corpus callosum (CC) is
currently controversial, possibly because of difficulties in morphometric
analysis.Clarke et al ,1989) The controversies may be due to differences in race
of subjects under study or differences in the method of measurement. In the
studies, there are groups stating that there are differences between male and
female in respect to (CC) morphometry,Se Bellis et al , 2001) as well as the
groups stating no difference.(Leonard , Takeda , et al 2003 ,2008) Ferrario et al
have
reported that effects are meaningful considering the age increase, while no
meaning in respect to genders,( Ferrario , et al 1996) .This was consistent with
our findings. Comparing with other Asian population (Kosar , etal (2012); CCI
for Sudanese is found to be greater. There are many causes which may affect
(CC) morphology; such as, demiyelizan diseases, congenital anomalies,
(Hayakawa , et al 1989) In such cases, for evaluation, besides the quantitative
methods of area, length, width, we believe usage of a reliability proven index
for Sudanese might be useful.
86
5-2 CONCLUSION
No significant difference in corpus callosum between both male and female
gender measurements -in CCI . there is a little difference in the size of the
corpus callosum with age -, it is clear that corpus callosum in the female larger
than male with elder age.
using MRI T1 weighted multi section sagital
conventional give better accurate estimate of measurement
87
5-3 RECOMMENDATION
Further studies to find the difference in carpus callosum measurements
with age -further studies on sick people . and people who are not sick . for
more knowledge -use software technology instead of the equation. Case
100 divided by 50 female and 50 male.
It is useful to provide basic data for measurements of the carpus callosum
even be compared in the event of a disease.
88
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APPENDICES
Appendix (1) Chart of data Collection as proposal to be filled
93
Female Sudanese populations /50
‫م‬
age
Brain AP
Length
Cc length
Thickness genu Thickness body
Aa
Bb
94
Thickness
splenum
cc
Cci
Aa+bb+cc
ab
Brainb AP
sagtal
Brain Ap
oxial
Brain
transvere
oxial
Female Sudanese populations /50
‫م‬
age
Brain AP
Length
Cc length
Thickness genu Thickness body
Aa
Bb
95
Thickness
splenum
cc
Cci
Aa+bb+cc
ab
Brainb AP
sagtal
Brain Ap
oxial
Brain transvere
oxial
Male Sudanese populations /50
‫م‬
age
Brain AP
Length
Cc length
Thickness genu Thickness body
Aa
Bb
96
Thickness
splenum
cc
Cci
Aa+bb+cc
ab
Brainb AP
sagtal
Brain Ap
oxial
Brain transvere
oxial
Male Sudanese populations /50
‫م‬
age
Brain AP
Length
Cc length
Thickness genu Thickness body
Aa
Bb
97
Thickness
splenum
cc
Cci
Aa+bb+cc
ab
Brainb AP
sagtal
Brain Ap
oxial
Brain transvere
oxial
Appendix (2)
Image
In figure ((1)) Female age 42 year old – segatal T1 of CC
Measure was taken in italics passing through the body
In figure (( 2)) Female age 42 years old
Measurements was taken casual line going through Genu and splenium
98
In figure (( 3 )) Female
The corpus callosum measure starting from Genu until splenium
In figure (( 4 )) Female
Measurements was taken in italics began in Genu and ended with Rostrum
99
In figure (( 5 )) Female
The body was taken to measure vertical line
In figure ((6 )) Female
Splenium measure was taken in italics
111
In figure (( 7 )) Female
It was taken to measure the Brain s casual line
In figure ((8 )) Female
It was taken to measure Brain longitudinal line
111
In figure (( 1 ))Male – age 47 years old
Measure was taken in italics passing through the body
In figure ((2 ))Male
Measurements was taken casual line going through Genu and splenium
112
In figure ((3))Male
Measurements was taken in italics began in Genu and ended with Rostrum
In figure ((4 ))Male
Splenium measure was taken in italics
113
In figure ((5)) Male
The body was taken to measure vertical line
In figure ((6)) Male
It was taken to measure Brain longitudinal line
114
In figure ((7)) Male
It was taken to measure the Brain s casual line
Figure ( 8) : The sagittal plane of T1-weighted image of head magnetic resonance imaging (MRI). The
corpus callosum
115
Magnetic resonance imaging in the user's machine samples
Magnetic resonance imaging in the user's machine samples.
116
‫م‬
age
Brain AP
Length
Cc length
Thickness genu Thickness body
Aa
Bb
117
Thickness
splenum
cc
Cci
Aa+bb+cc
ab
Brainb AP
sagtal
Brain Ap
oxial
Brain transve
oxial